The main computer of your vehicle (PCM/ECM/ECU), triggers the fault code P0137 if it detects an oxygen sensor voltage below the pre-programmed parameters by the manufacturer for a period of time. The code indicates an excess of oxygen in exhaust system. This means the engine is running lean (lean mixture = excessive air + insufficient fuel). The sensor 2 is the downstream O2 located after the catalyst converter. Sensor 1 is also called the sensor that is located in front of the catalytic convert. The outlet sensor is located after the catalytic convertor.
Understanding O2 sensors is essential to understanding the P0137 error code. O2 sensors upstream (sensor 1) create variable voltages which allow the PCM adjust the air/fuel mixture to be rich or lean. When the catalytic convertor is working properly, downstream sensors (sensor 2) produce a relatively stable voltage.
The P0137 fault is activated if the PCM detects the signal from Bank 1 sensor 2 is below a specified value for a period of time.
Note: P0137 indicates almost the same issue as P0136. The P0137 code indicates that the O2 sensor voltage is sending a low-voltage signal for over 2 minutes.
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What are the possible causes of fault code P0137?
P0137 is an all-purpose fault code. It can be found on a wide range of vehicle models. The description of the fault may differ from one vehicle to another. In Toyota, for example, the code P0137 means “Heated Oxygen Sensor Circuit Low Voltage Bank 1 Sensor 2”. Chevrolet describes it as ‘Heated Oxygen Sensor Circuit Low Voltage Bank 2, Sensor 2’. The possible causes can vary based on the make and model of your vehicle.
- Faulty oxygen sensor
- Lean operating condition
- A problem with the O2 Sensor Circuit
- A leaky exhaust
- Catalytic converter clogged
- Misfiring engine
- Fuel pressure too low or high
- Fuel regulator or pump
- PCM software that is outdated
What are the symptoms of fault code P0137?
- The engine fault light is usually the only symptom of the P0137 error code.
- Leaks or bad odours coming from the exhaust
How to Fix Fault Code P0137?
- Replace the O2 Sensor (Sensor 2, Bank 1)
- Repair or replace cable or connection to the sensor
- Clean your O2 sensor, if you have contaminated it due to oil or coolant leaks
- Fix any exhaust leaks prior to the sensor. This causes air into the exhaust system, resulting in a low O2 reading.
- Check for possible damage to the O2 sensor caused by the catalytic convertor. If the catalytic convert is damaged, replace it.
How Serious Is the P0137 Fault Code?
PCM will not be able to control the air-fuel mix properly if any O2 sensors are faulty. If this fault is not corrected, it may lead to premature failure of certain engine components, damage on the catalytic convertor, decreased engine performance, and increased fuel consumption.
