Symptoms of a malfunctioning oxygen sensor (lambda probe) and how to fix them

The lambda probe is an oxygen controller. It is used to control and balance the proportions of air and fuel during the formation of a combustible mixture. Correct functioning of the element will prevent destabilization of the motor's operating process. To determine the cause of the breakdown, you need to know the signs of a malfunctioning lambda probe.

External signs and causes

If the lambda probe heating system or the device itself in the car does not work, the symptoms of the malfunctioning condition will be as follows:

1. The power unit began to operate less stably. The revolutions can spontaneously increase and fall. The engine often stalls, especially at traffic lights.
2. The quality of the combustible mixture, which is pumped with air into the cylinder system, has decreased. If the sensor is not functioning properly, this will cause excessive fuel consumption.
3. The fuel supply has become ineffective, fuel enters the combustion chambers uncontrollably. This can lead to malfunctions in the operation of the unit, as well as the electronic system of the car.
4. Over time, the engine may experience intermittency when operating at idle speed. At maximum, the efficiency of the internal combustion engine will also be less low.
5. There were problems with the functioning of electronic systems. Due to the need to repair the sensor, individual compartments of the power unit will operate unstably. This is due to the fact that pulsed fault signals are sent with a delay.
6. While driving, the vehicle began to jerk. Especially when the car is going uphill.
7. When the engine operates at any speed, popping noises may appear.
8. The engine began to respond slowly to pressing the gas pedal. Acceleration occurs, but not immediately.

One of the important symptoms is the lightning of the Check Engine indicator or the oxygen controller failure light on the car’s dashboard.

The reasons why the performance of the oxygen sensor will be impaired may not arise immediately, so failure of the part occurs in several stages:

1. At first, the oxygen sensor begins to function unstably. Periodically, the signal from the device disappears, information is provided over a wide range. This leads to deterioration in the quality of the combustible mixture, as well as unstable speed operation. At the initial stage, the car jerks when moving, popping noises uncharacteristic of the operation of the internal combustion engine appear, and a malfunction indicator may light up on the dashboard.
2. At the next stage, the lambda probe stops functioning on a cold engine until the unit warms up. The symptoms of the problem will be similar, only they will appear with greater force. The engine power of the car may decrease, and a response will appear when you press the gas pedal. As a result, this can lead to overheating of the internal combustion engine.
3. At the third stage, the oxygen sensor usually fails completely. The power of the power unit drops even more, this is clearly evident when driving at high speed. An unpleasant and pungent odor appears from the muffler.

Reasons that may cause a breakdown of the oxygen sensor:

1. The device casing has depressurized. Because of this, exhaust gases and air began to get inside.
2. Controller overheating. The reason may be due to malfunctions in the ignition system or incorrectly performed tuning of the power unit.
3. Long-term exposure to external factors. This reason can be attributed to natural wear and tear, since any oxygen sensor fails over time.
4. The working surface of the oxygen sensor is covered with combustion products, which block its operation. This is usually due to the regular use of low-quality fuel.
5. There is a power failure or the wiring leading to the central control unit is damaged.
6. Mechanical damage to the device. A strong blow to the case may destroy the internal components of the controller. This often occurs during regular off-road driving.

The “Online auto parts store” channel talked about the causes of malfunctions in the operation of oxygen controllers.

Is it possible to clean the probe?

If an oxygen sensor breaks down, you cannot do without replacing it, since there are no methods for restoring it. Considering the high cost of spare parts, repairs can be accompanied by considerable expenses.

But there are other options:

• select a universal sensor, which is much cheaper than the original and is suitable for most car models;
• They are looking for a used part with a guarantee; an exhaust manifold with an installed sensor will do.

But it is not always necessary to change the spare part. It is enough to know how to clean the lambda probe. After all, situations of severe pollution cannot be ruled out. Particles of soot and soot may be deposited on the sensitive element, covered with a protective cap. Because of this, problems and errors appear in the work. Once the plaque is removed, the effectiveness of the device is restored.

Subtleties of cleaning:

1. The procedure begins with dismantling, for which the surface of the part is heated to 50 degrees. Having removed the sensor, remove the protective cap.
2. The work uses orthophosphoric acid, which can remove carbon particles and contaminants without damaging the electrodes and important elements. Soaking is carried out for 10 - 20 minutes.
3. A more complex option involves removing the protective cap and washing it using a very thin brush. After removing contamination, the part is washed and dried.

Washing is carried out if it is possible to re-fasten the protection, which involves argon welding. The cost of cleaning is much less than replacement. This solution is only suitable for serviceable but dirty sensors. During subsequent fastening, it is important to lubricate the threaded connection with mounting paste. When installing a new element, no lubrication is required; the connection is processed during production.

Purpose and operation of the sensor

To understand what the lambda probe is responsible for, it is worth paying attention to the operation of the fuel system. The oxygen sensor is an important element that allows you to maximize engine efficiency on injection machines.

High performance is possible with complete combustion of the air-fuel mixture. Therefore, it is important to determine the optimal proportion of components. Thanks to the correct assessment of the oxygen content in the exhaust, a subsequent calculation of the composition of the fuel mixture is performed.

A properly functioning probe provides:

• reduction in fuel consumption up to 15%;
• increasing the environmental friendliness of exhaust gases;
• the factory service life of the catalyst is preserved;
• Excellent dynamics and responsiveness during control are maintained.

The best performance is typical for cars with two sensors, where one is located before the catalyst, and the second after it.

When studying the principle of operation of a lambda probe, it is worth considering that the operating pattern differs depending on the type.

Device types:

1. Two-point models include two electrodes in their design. This makes it possible to estimate the coefficient of excess oxygen in the fuel mixture by determining its content in the exhaust. The action occurs during the passage of exhaust gases. Here the first element is sensitive to oxygen. The second one is made of zirconium. As the exhaust passes between the electrodes, the potential is measured. An increase in the indicator means excess oxygen content.
2. Broadband represents a new type of probe. A voltage of 450 mV is maintained here. The device includes ceramic components - two-point and pumping. The latter draws in oxygen present in the exhaust. In this case, a certain amount of current is used. A drop in oxygen level leads to an increase in voltage, which is accompanied by a corresponding signal from the ECU.

Care, timely diagnostics, and troubleshooting allow you to eliminate most unforeseen situations, preserve the factory resource and functionality of the units.

How to check with a multimeter

Before diagnosing the oxygen sensor itself, its heating device is checked.
The tester can check the operation of the heating component of the oxygen sensor:

1. The diagnostic device switches to the resistance parameter measurement mode.
2. The probes of the device are connected to the heater contacts. These elements are usually made of cable with a large cross-section.
3. The contacts of the heating device are ringing.
4. If the heating element is working, then the resulting resistance value will be less than 10 ohms. If this parameter is higher, then the electric heating device has failed and needs to be replaced.

The tester checks like this:

1. Locate the controller mounting location under the hood of your vehicle.
2. Connect the multimeter probes to the signal outputs of the sensor or electrical circuits. The tester itself sets the measurement limit to 2 volts.
3. At the next stage, it is necessary to artificially create a situation of an over-enriched combustible mixture. To do this, you can use the throttle change method by periodically pressing the gas pedal. Or you can remove the pressure sensor connector.
4. Then the readings given by the tester are read. Ideally, they should be from 0.8 volts, this indicates that the oxygen sensor is working properly.
5. It is necessary to artificially create a lean mixture situation. To do this, you can create an air leak by slightly loosening the air duct clamp. With a lean mixture, the tester reading should be no more than 0.2 volts.

V_i_t_a_l_y talked about diagnosing the oxygen controller using a multimeter.

Restoring correct operation of the λ-probe

Error codes will need to be reset from the ECU after troubleshooting. Moreover, if the cause is low-quality gasoline, you will have to drain it and fill it with high-quality fuel. And only after that reset the codes.

If breaks are detected, you need to solder the connected parts.

Clean dirt and carbon deposits with active reagents.

The lambda probe is a consumable item. If you have diagnosed its final breakdown, then it needs to be replaced. It cannot be repaired, since damaged precious metal threads cannot be replaced, even at dealer service centers.

You can replace the old probe with an original or universal device from Bosch. Mounting with an adapter makes it suitable for any make of car. When installing a new sensor, do not forget to lubricate its threaded part with sealant.

Timely replacement of the lambda probe, even if it has simply exhausted its service life, will increase engine power and ensure its uninterrupted operation.

Other diagnostic methods

If signs of a lambda probe malfunction appear, you can use computer diagnostics to check its functionality. It allows you to monitor the operating parameters of the oxygen sensor online.

You can use an oscilloscope for diagnostics. If the test shows that the lower limit of the device drops to zero volts, then the controller is working, but it will need to be changed soon. If the time dependence of the voltage at the signal contact is characterized by greater smoothness, then it is time to replace the sensor.

It is correct to start diagnosing four-pin oxygen sensors with a visual inspection; this procedure is recommended to be performed every 10 thousand kilometers. For testing, the controller is removed from the manifold; WD-40 or brake fluid cannot be used, since their contact with the working surface will cause it to break. If special means are used when unscrewing coked threads, their residues are removed before removing the device.

Assess the color and condition of the operating area of ​​the oxygen controller. If traces of soot are visible on it, this indicates an over-enriched combustible mixture in the engine. Its presence leads to contamination of the device, so to ensure better performance, soot must be removed. A gray or white coating indicates the use of additives in motor fluid or fuel. The presence of a shiny coating indicates that the concentration of lead in the fuel used is exceeded. If the coating is intense, then the sensor cannot be repaired; it must be replaced.

Symptoms of lambda sensor failures

The device has a limited service life, intended for a maximum mileage of 150,000 km. However, in practice, already at 80 thousand mileage problems begin in this device. If you do not replace a faulty device in time, this will lead to breakdown of the catalyst. Buying and replacing a catalyst will cost you a pretty penny.

The driver himself can understand when something is wrong with the sensor.

• When in idle mode, “triple” is felt, but the ignition is working properly;
• A noticeable increase in fuel consumption;
• Dips in acceleration, variable dynamics, loss of power;
• And, of course, the “CHECK ENGINE” button lit up.

A faulty sensor causes the formation of heavy carbon deposits throughout the entire fuel system and the formation of smoke in many important parts, which results in their incorrect operation or failure.

Instructions for repairing and replacing the sensor

You can replace or restore the controller yourself.

How to remove the sensor

Removing the device, regardless of the machine model, is done as follows:

1. Warm up the surface of the part to approximately 60 degrees. To do this, you can use a regular lighter or torch. Warming up will make it easier to remove the device from the seat.
2. Disconnect the wires connected to the part.
3. Carefully unscrew the oxygen sensor. It is not recommended to use special tools for dismantling.
4. Remove the protective cap.

Diman Stepanenko spoke about dismantling the lambda probe on his own.

Cleaning and Soaking

There are two options for restoring the oxygen sensor:

• the first - using orthophosphoric acid;
• the second - with phosphoric acid and a burner.

It must be taken into account that phosphoric acid or another similar product belongs to the category of hazardous substances. When working with a substance, it is important to remember safety rules. Acid should not be allowed to enter the mucous membranes or inside the body.

First way

This method cannot be called accelerated, since the consumer needs to gain full or at least partial access to the ceramic surface of the device. This component is hidden behind a protective cap made of metal; it is not easy to dismantle. Do not use a hacksaw for removal as it will damage the work surface. Dismantling is carried out using a lathe - at the base of the oxygen sensor, you need to cut off the protective cap using a cutter. The cutting is done close to the thread.

If it is not possible to use the machine, you can use a file. It is not possible to completely remove the cap with this tool, but you can make small windows about 5 mm in size on it. Approximately 100 ml of orthophosphoric acid is used for cleaning. If it is not available, you can use a rust converter.

Device recovery:

1. Pour the liquid into a glass container. You can use jars, glasses, etc.
2. Place the oxygen sensor core into the container. The controller cannot be completely immersed in liquid. Wait about twenty minutes.
3. Remove the sensor from the container and rinse its base with tap water. Wait until the device is completely dry.
4. If you are unable to remove the dark deposits on the core the first time, repeat the procedure. It is necessary to ensure that the element again becomes a metallic color.
5. If, after several attempts, high-quality cleaning fails, you can use a brush to enhance the effect of the product. The base of the device is wetted and treated with it. As a result, the plaque should be removed. If the protective cap has been removed, then the brush will not be needed. It is better to use a toothbrush instead.
6. After cleaning has been completely completed, the sensor is washed. If the cap has been removed, then after restoration it must be put back in place. For this, argon welding is used.

When using this method, please note:

1. If the device is heavily soiled, then twenty minutes will not be enough to restore it. For critical blockages, the soaking procedure can be extended to three hours. In some situations, cleaning may take a full night, at least eight hours.
2. After cleaning, you need to check how effectively the procedure was performed. Diagnostics will require some time for the car owner to understand how the car behaves and how much fuel it “eats.” If the malfunction indicator on the device remains lit, then the controller could not be repaired.
3. If the machine is equipped with a sensor whose protective cap is equipped with a double shell, then it will not be possible to make a hole in it with a file. To solve the problem, you need to soak the device in acid or another product with the cap itself.

The process of cleaning the oxygen controller is shown by Alexander Sabegatulin.

Second way

To restore the controller you will need the same acid, as well as a gas burner or stove. When using a household stove, give preference to a small burner.

Cleaning procedure:

1. The lid is removed from the burner. Then it is turned over and installed back, with a slight offset to the side. It is necessary to install the lid so that it covers the pipe itself from liquid getting inside.
2. The fire on the burner is lit.
3. The lambda probe core must be dipped in a container of acid, then taken with pliers and heated over a fire. This will cause the acid to boil and the substance will begin to splash. A greenish tint of salt will appear on the working surface of the device.
4. Wait until the substance has completely boiled away. Rinse the controller with clean water and then repeat the cleaning procedure. These steps must be continued until the controller is completely shiny. This may take ten minutes or more. Before further installation, the thread of the lambda probe must be treated with graphite lubricant, which will prevent the oxygen sensor from sticking to the threaded hole.

Installing a lambda probe

Installation of the device is carried out in the reverse order:

1. A protective cap is installed on the sensor.
2. Wires are connected to the device.
3. The controller is installed in the seat and screwed in.

The need to warm up the oxygen sensor

To start working, the oxygen sensor requires the sensing element to be heated to a certain temperature. During engine operation, this is ensured by the temperature of the exhaust gases, especially on modern engines with catalytic collectors, where the upper lambda probe is installed close to the cylinder head.

Initially, lambda probes did not have any heating circuits - you can encounter such sensors, for example, on old “Japanese” ones (single-wire, where the signal “ground” goes through the exhaust pipe to the engine, and more accurate two-wire ones with a separate signal “ground”). At a time when the severity of environmental standards was incomparable to today, the lack of correction by the lambda probe during engine warm-up was not critical: the engine warmed up with a knowingly rich mixture. Already as the signal at the output of the lambda probe began to change, the electronic control unit (ECU) switched to an algorithm, including feedback from the oxygen sensor.

Subsequently, environmentalists paid close attention to this regime. Automakers had to ensure that the injection system was brought to a “closed loop” as quickly as possible in order to meet the requirements of environmental standards. This is how heated oxygen sensors appeared, first wire, and then ceramic.

As soon as you turn on the ignition, the injection ECU carries out an initial test of itself and peripheral circuits, including the heating of the oxygen sensor. By the time the engine starts, it has already warmed up, finally reaching operating mode with minimal delay. But this also arose the possibility of an “extra” malfunction.

Monitoring the integrity of the heater occurs in the ECU very simply - by the voltage drop across a resistor of very low resistance (hundredths of an ohm) connected to the circuit of the transistor that controls the heating. When everything is normal, in full accordance with Ohm's law for the complete circuit, there is a small voltage on this transistor, which is regarded by the ECU controller as normal operation of the heater. But if there is too much resistance in the circuit BEFORE this resistor or its complete break, the voltage across the measuring resistor becomes zero. The controller, having detected this, goes into emergency mode and stores error P0135.

How to make a corrector (fake) lambda probe?

There are several types of correctors for oxygen controllers. The mechanical device is the simplest and most affordable in terms of corrector design. It is necessary to machine a special adapter into which the lambda probe is installed, as well as a mini-catalyst. After this, the assembled device is mounted in the standard place of the car muffler.

If the catalyst device or the oxygen sensor installed after it breaks down, a signal will be sent to the control unit. The module will be warned that the exhaust gases contain harmful substances, the volume of which exceeds the permissible value. The control unit will perceive this event as an emergency and increase the fuel supply to enrich the air-fuel mixture.

When installing such a corrector, exhaust gases will flow through a small hole in the adapter into the catalyst device. The latter is filled with ceramic dust with a catalytic layer. The concentration of harmful substances in the exhaust gases will be lower. The control module will perceive this as the correct operation of the controller and standard catalyst device. The manufacture of blende is carried out using a lathe and a diagram; steel or bronze can be used as a material.

Scheme of a mechanical corrector for a lambda probe

Universal drawings that can be found on the Internet may not be suitable for making a lambda probe blende for a specific car model; you need to look for a proven option.

Making an electronic controller fake:

1. Using the SprintLayout program and a printer, a layout drawing and arrangement of circuit elements are printed. Printing is done on glossy paper.
2. When sending a file for printing, you must select 100% black for layer K1. In the program, check the box next to Mirror and Scheme Outline. All other layers are deleted.
3. Then the next layer is sent for printing. For the M2 layer, the color is black. The checkbox opposite the Mirror item is removed, but it remains opposite the second element. Other layers are removed.
4. When performing the task, it is recommended to use foil textolite. It must be one-sided, and its thickness will be no less than 1 and no more than 2 mm.
5. When the printout is in hand, it must be transferred to the LM324 board using an iron. The board itself is cut out taking into account the dimensions, and printouts must be made along its contour. After cutting, attach the diagram to the drawing; the dimensions must match exactly.
6. Using fine-grained sandpaper, the copper layer is cleaned. The board is cleaned using fuel or solvent.
7. Then you need to transfer the printout with the tracks to the working surface of the board. A printed layer of elements is installed on the reverse (copper surface). To do this, foil paper is applied to the board and heated with an iron; the procedure takes no more than 10 minutes. When warming up, the surface of the iron should be pressed as close as possible to the board. As a result, the toner should be reprinted from the foil surface onto the circuit. If the paper density is low, the tracks will be visible. The problem can be corrected using a permanent black marker.
8. The next step will be etching, this will require ferric chloride or sodium perchlorate.
9. Then holes are drilled on the board and the elements are soldered.
10. At the final stage, the operating parameters of the corrector are adjusted. To do this, +950 mV is supplied to the input, and the voltage value is adjusted in the range from 950 to 1000 mV. For the LM324 board, the procedure is done by setting up elements VR3 and VR4.

Circuit for making electronic decoy

Printout of the circuit for installation on the board

Connecting all components on the decoy board

Is it possible to drive with P0135?

Older injection systems initially retain a “wait” for warming up, that is, in the worst case, fuel consumption will slightly increase (due to the fact that reaching the “closed loop” during warming up will begin to lag). Many cars easily drive several thousand until the owner gets tired of the Check Engine light being on.

In the future, this emergency algorithm was preserved, the only “but” in the larger “choke” under strict economic standards. That is, a modern car will not experience serious problems with faulty heating if the sensor itself is working properly.

However, if the error occurs randomly (that is, after a reset, not immediately after turning on the ignition, when the self-test is running, but with a random delay or even while driving), then this indicates more serious problems. Thus, there are known cases when, to eliminate error P0135, dealers replaced defective wiring harnesses on Kia Ceed. If the error occurs due to a bad contact on the ECU connector, then it is unlikely that the problem is only in one contact out of several dozen (or even more than a hundred), there may be further “surprises”.

What is the price?

The cost of the device will vary depending on the manufacturer and brand of the machine.