Many brand car owners Nissan, especially models Qashqai and X-Trail, are faced with the appearance of the Check Engine indicator on the dashboard. The scanner often issues a code P0139, which indicates incorrect operation of the second oxygen sensor. This is not just a flashing light, but a signal that the electronic engine control system (ECU) has ceased to receive reliable data on the composition of the exhaust gases after the catalyst.
Ignoring such a problem can lead to increased fuel consumption, worse acceleration dynamics and, in the worst case, failure of an expensive converter. Understanding the nature of this error will allow you not only to save time on a service visit, but also to avoid unnecessary costs for replacing working components.
The essence of the fault code and system operation
Error P0139 stands for "Oxygen Sensor Circuit Bank 1 Sensor 2: Slow Response." The technical documentation describes this as a situation where the voltage at the output of the second lambda probe changes too slowly or remains static for a long time.
Unlike the first sensor, which is responsible for correcting the fuel mixture, the second oxygen probe serves as a monitor for the efficiency of the catalytic converter. It is located directly behind the catalyst in the exhaust system. If its readings do not correspond to the expected patterns, the ECU records a failure.
It is necessary to understand that a slow response may indicate either physical aging of the sensor or a problem with the electrical circuit. Sometimes the signal simply does not reach the processor due to oxidized contacts or damaged wiring, which often happens in harsh winter conditions on roads with reagents.
The main reasons for the failure
List of probable causes of the code P0139 is quite extensive, but most of them are due to physical wear and tear or electrical problems. Most often, the problem lies in the sensor itself, which loses sensitivity over time.
- 🔥 Natural wear and tear of the element lambda probe and contamination of its sensitive tip with combustion products.
- ⚡ Break or short circuit in the wiring running from the sensor connector to the engine control unit.
- 🔌 Oxidation of contacts in the connection connector, which leads to poor contact and unstable signal.
- 💨 Malfunction of the heating element inside the sensor, due to which it does not enter operating mode.
It is also important to exclude mechanical damage to the exhaust manifold or the catalyst itself. The influx of foreign air into the exhaust system can distort the readings, and the ECU mistakenly interprets this as a slow sensor response.
Sometimes the reason lies in problems with the catalyst itself. If it is destroyed or clogged, the flow of gases is disrupted and the second sensor cannot generate the correct signal. In this case, replacing only the probe will not solve the problem.
⚠️ Attention: Do not try to fix the error by simply deleting the code with a scanner. Without correcting the physical cause (such as replacing the sensor or repairing the wiring), the P0139 code will return after a few driving cycles.
Diagnostics and testing of the electrical circuit
Before purchasing a new sensor, it is necessary to conduct a thorough inspection of the electrical part. Owners Almera and Teana It's worth starting with a visual inspection of the wiring. Look for melt marks, chafed insulation, or signs of corrosion on the connectors.
For an accurate diagnosis, you will need a multimeter. Check the resistance of the heater circuit. Typically it should be in the range of 2 to 14 ohms, but the exact values depend on the engine model. If the resistance is infinitely high or equal to zero, the heater is faulty.
Next, you need to check the signal at the sensor output. Connect a voltmeter to the signal wire and start the engine. On a warm engine, the voltage should fluctuate smoothly between 0.1 and 0.9 volts. If the meter needle stays still or moves too slowly, the sensor needs to be replaced.
- 🛠 Use a multimeter in resistance mode to check the continuity of the circuit.
- 📉 Monitor voltage in real time via OBD2 scanner or oscilloscope.
- 🔍 Inspect the connectors for mechanical damage and contact oxidation.
- Do it yourself with a multimeter
- In the service on your computer
- Just reset the error
- Haven't checked yet
Step-by-step instructions for replacing the sensor
If diagnostics confirm a malfunction of the sensor itself, it must be replaced. This procedure does not require sophisticated equipment, but it does require accuracy, especially if the car has been in use for a long time. The sensor may be stuck to the thread.
First you need to turn off the power to the car and wait for the exhaust system to cool completely. Hot parts can cause serious burns and also damage new O-rings.
Disconnect the connector from the sensor. It is often located in a hard-to-reach place under the car. Use a special wrench for the lambda probe or a spanner of the appropriate size. Carefully unscrew the old element, being careful not to damage the threads on the exhaust pipe.
☑️ Preparation for replacement
Before installing a new sensor, apply a special heat-resistant lubricant to the threads. This will ensure easy installation and, importantly, allow the sensor to be easily removed in the future. Do not use regular motor oil or graphite grease as they may contaminate the sensor element.
- 🔧 Apply some non-stick paste to the threads of the new sensor.
- 🔩 Screw the new element by hand until it stops, then tighten it with a wrench with the force specified in the instructions.
- 🔌 Connect the electrical connector until it clicks into place.
If the sensor does not come off, use a penetrating lubricant (such as WD-40) and let it sit for 15-20 minutes before attempting to remove it.
Comparison table of sensors for popular models
Selecting the correct sensor is critical to the correct operation of the system. Below is a table with approximate part numbers and characteristics for popular models Nissan.
| Car model | Original number | Analogue (replacement) | Location |
|---|---|---|---|
| Qashqai (J10) | 22690-1AA0A | Bosch 15893 | Behind the catalyst |
| X-Trail (T31) | 22690-EN00A | NGK O2S134 | Behind the catalyst |
| Teana (J32) | 22690-31U0A | Denso 234-9018 | Behind the catalyst |
| Almera Classic | 22690-41U0A | Harber 561 | Behind the catalyst |
Please note that the use of non-original low-quality parts may lead to the reappearance of error P0139 after just a few thousand kilometers. Saving on a sensor often results in the need to purchase a more expensive part later.
What should I do if the error returns after replacement?|If the P0139 error appears again immediately after installing a new sensor, check the integrity of the catalytic converter. Perhaps it is destroyed and allows excess oxygen to pass through, which throws off the readings. It is also worth checking the air leaks in the intake manifold.-->
Software methods for solving the problem
Sometimes physically replacing the sensor does not help, and a software adjustment is required. This can happen if the catalyst was replaced with a flame arrester or if a sensor with different characteristics was used.
In such cases, you need to contact a professional chip tuner. He can reflash the ECU by disabling control of the second lambda probe or adjusting the catalyst operation algorithm. This is a legal method if you have replaced the catalytic converter with a cheaper alternative.
However, it is worth remembering that disabling catalyst control can lead to increased exhaust emissions, which is prohibited by law in some regions. It may also affect the operation of the Exhaust Gas Recirculation (EGR) system.
⚠️ Attention
Software disabling the second oxygen sensor does not eliminate the cause of the slow response, but only hides the error. If the sensor fails due to engine failure, the problem will remain.
Prevention and operating tips
To avoid the error reappearing P0139, you must follow simple operating rules. Use high-quality fuel, as low-grade gasoline with a high content of additives quickly “kills” lambda probes.
Check the condition of the spark plugs regularly. Misfires result in unburned fuel entering the exhaust system, where it burns out, overheating the catalyst and sensors. This is one of the most common causes of premature failure.
If you plan to park your car for a long time, disconnect the battery or periodically start the engine to warm up the exhaust system and avoid moisture condensation, which can lead to corrosion of the contacts.
It is also recommended to diagnose the exhaust system once a year, especially if the car is operated in off-road conditions or in frequent temperature changes. This will help identify microcracks in the reservoir before they lead to serious consequences.
What does error code P0139 mean on Nissan Qashqai?
Error P0139 indicates that the second lambda probe (located after the catalyst) responds too slowly to changes in the composition of the exhaust gases. This could be caused by a worn sensor, wiring problems, or a faulty catalytic converter.
Is it possible to drive with P0139?
You can drive, but it is not recommended for a long time. The car will go into emergency mode, fuel consumption and exhaust toxicity will increase. Additionally, if the catalytic converter is the problem, its destruction can allow ceramics to enter the engine.
How much does it cost to replace a lambda probe on a Nissan?
The cost of the original sensor varies from 3,000 to 8,000 rubles, depending on the model. Replacement work at the service center will cost approximately 1000-2000 rubles. Installing analogues is much cheaper, but their service life may be shorter.
How to reset P0139?
The error is reset via the OBD2 diagnostic scanner after the cause of the malfunction has been eliminated. If you simply disconnect the battery terminal, the error may be stored in the ECU memory or return after several engine starting cycles.