A malfunction in the engine management system is often accompanied by an illuminated Check Engine light, and one of the most common causes is a trouble code P0137. On brand cars Nissan This parameter signals that the second oxygen sensor (Bank 1, Sensor 2) produces a voltage below the permissible threshold for a certain time. Ignoring this problem can lead to increased fuel consumption, unstable engine idling, and even failure of the catalytic converter, which is an expensive component.

For owners of such popular models as Nissan Qashqai, Nissan X-Trail or Nissan Teana, understanding the nature of this error is critical. Unlike a simple electronic failure, the P0137 code often indicates a physical problem in the exhaust system or power circuits. You need to conduct thorough diagnostics to eliminate false alarms and accurately determine whether the situation requires replacing the sensor or whether the problem lies in the wiring.

The essence of the malfunction and the principle of operation of the system

To understand why the error occurs, you need to understand the operation of the engine control system. The oxygen sensor, or lambda probe, located after the catalyst, is responsible for monitoring the efficiency of the converter. It measures the residual oxygen content in the exhaust gases and transmits this signal to the engine control unit (ECU).

During normal operation, the sensor should generate a voltage in the range from 0.1 to 0.9 volts, constantly changing it depending on the composition of the mixture. Code P0137 is set when the ECU registers voltage below 0.15 volts for 20-30 seconds. This means that the sensor “sees” too much oxygen or is simply “silent”, not transmitting valid data.

It is important to distinguish between the first and second sensors. The first one stands before the catalyst and regulates the mixture, and the second one stands after it, monitoring its efficiency. An error in the second sensor (Bank 1 Sensor 2) most often indicates problems with the catalytic converter itself or exhaust gas leaks, although the measurement element itself is often the culprit.

On turbocharged vehicles such as Nissan Juke or Nissan Note with DIG-T engines, the control system operates in more aggressive modes, which accelerates the wear of exhaust system elements. If you notice that the error appears intermittently, especially on a cold engine, this may be a sign of incipient failure of the probe's heating element.

Common Causes of Code P0137

The list of potential culprits for a malfunction is wide, and diagnosis should begin with checking the most likely and cheapest causes to eliminate. You should not immediately run to the store for a new sensor, as often the problem lies in the wiring or mechanical damage.

The most common cause is an open or short circuit in the sensor signal circuit. The wires leading to the oxygen sensor are in an area of ​​high temperatures and vibrations, which over time leads to chafing of the insulation or oxidation of the contacts. It is also possible that the wiring harness itself may be damaged by rodents, which often happens in the autumn-winter period.

Another common cause is a malfunction of the oxygen sensor. Over time, the sensitive element becomes contaminated with combustion products of oil or antifreeze, which reduces its sensitivity and leads to inflated voltage readings. In some cases, the sensor simply “dies” due to natural wear and tear of the resource.

An equally critical reason may be a physical leak of exhaust gases to the sensor. If there is a crack in the exhaust pipe, manifold or downpipe gasket, atmospheric air is sucked in. The sensor detects excess oxygen and produces a low voltage, which the ECU interprets as error P0137.

  • 💥 Open circuit of the signal or mass of the oxygen sensor
  • 🔌 Oxidation or corrosion of contacts in the connector
  • 🔥 Malfunction of the sensor heating element
  • ⚙️ Exhaust gas leak due to a burnt gasket or crack

Diagnostics and troubleshooting

The first step in diagnosis is a visual inspection of the exhaust system and wiring. You need to find the oxygen sensor located after the catalyst and carefully inspect the wires going to it. Look for signs of melting, breaks, cracks in the insulation, or signs of scorching on the connectors.

If visually everything looks normal, you need to check the exhaust system for leaks. Start the engine and listen for the characteristic sound of air suction (“pshsh-pshsh”) in the area of ​​the manifold or exhaust pipe. You can also use a smoke generator to accurately locate leaks, but in a garage environment, a soap solution applied to the joints while the engine is running is often sufficient.

To accurately determine the malfunction, you will need a multimeter or diagnostic scanner capable of reading data in real time. Connect the device to the sensor connector and monitor the voltage on the signal wire with the engine running. Normally, the voltage should fluctuate, but with error P0137 it will be fixed at a level close to zero.

Pay special attention to checking the power supply and ground circuits. If the sensor is not receiving power or does not have a reliable connection to ground, it will not be able to generate a signal. Use Ohmmeter to check wire resistance and circuit integrity. The sensor heater resistance must be within the specifications specified in the repair manual.

⚠️ Attention: When checking the oxygen sensor circuit, be sure to disconnect the battery before starting wiring work to avoid short circuit and damage to the electronic control unit.

Sometimes the problem may be due to a fault with the ECU itself, although this is extremely rare. If all external components and wiring are in good condition, but the error persists, it is worth checking for errors in the control unit itself or try replacing the sensor with a known good one to confirm the diagnosis.

  • 🔍 Check the integrity of the wire insulation visually
  • 📉 Measure the voltage on the signal wire with a multimeter
  • ⚡ Check the resistance of the heating element
  • 🛠️ Clean the connector contacts from oxides and dirt
📊 Which diagnostic method do you use most often?
  • Do it yourself with a multimeter
  • In the service on the scanner
  • According to symptoms and intuition
  • I don't know how to diagnose

Step-by-step instructions for troubleshooting

If you determine that the problem is in the wiring, you need to restore the integrity of the circuit. This may require re-soldering contacts, replacing connectors, or laying new sections of wire. Use heat-resistant wire with a cross-section of at least 0.5 mm² and high-quality electrical tape or heat shrink.

When replacing the oxygen sensor itself, it is important to use original spare parts or high-quality analogues, such as Denso, Bosch or NTK. Cheap Chinese analogues often have unstable characteristics and can quickly fail, which will lead to the reappearance of the error. Before installation, apply a special heat-resistant lubricant to the threads so that the sensor can be easily unscrewed in the future.

If the cause was an exhaust gas leak, it is necessary to replace the manifold gaskets or weld cracks in the pipe. After repair, be sure to delete the error from the ECU memory using a diagnostic scanner. Warm up the engine to operating temperature and check if the error in the warm-up cycle disappears.

In some cases, it may be necessary to reflash the ECU or adapt new sensor parameters. This is relevant for modern models with complex control systems, such as Nissan Murano or Nissan Pathfinder. Make sure that all engine parameters correspond to factory settings after repair.

☑️ Diagnostics and repair P0137

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⚠️ Attention: After replacing the sensor, do not forget to clear the error memory, otherwise the Check Engine lamp may remain on even with a working sensor, since the ECU still stores old data.

Take precautions during operation: the exhaust system becomes very hot, and working with it immediately after a trip can result in burns. Allow the engine to cool before starting work, especially if you need to remove a sensor or inspect the manifold.

  • 🛠️ Use a special key to remove the oxygen sensor
  • 🔥 Allow the exhaust system to cool before starting work
  • 🧼 Clean the installation site from dirt and rust
  • 📱 Take a photo of connecting the wires before disconnecting
What to do if the P0137 code returns?|If the code returns after replacing the sensor and checking the wiring, check for vacuum leaks in the intake system. It is also possible that the catalytic converter is completely damaged and needs to be replaced. In rare cases, the problem may be in the engine control unit itself.-->

Specifics of Nissan models and repair nuances

On different models Nissan Sensor locations and types may vary. For example, on Nissan Qashqai with the HR16DE engine the sensor is located in an accessible location, and on Nissan X-Trail with a turbo engine, access may be difficult due to the tight layout of the engine compartment. Always review the service documentation for your specific model.

A feature of the MR and QR series engines is their high sensitivity to fuel quality. Using low-quality gasoline can quickly poison the oxygen sensor with lead or other impurities, which will cause error code P0137 even with good wiring. In such cases, replacing the sensor without eliminating the cause (fuel quality) will not give a long-term result.

For models equipped with direct fuel injection (GDI), diagnostics may be more difficult because the control system operates within narrower ranges. Here it is important not only to check the sensor itself, but also to make sure that the injectors and fuel pump are operating correctly. The error may be due to a lean mixture caused by a malfunction of other components.

On older models such as Nissan Primera or Nissan Almera first generation, there is often a problem with oxidation of contacts in connectors due to lack of protection from moisture. In such cases, simply cleaning the contacts and treating them with contact spray can eliminate the error without replacing expensive parts.