What Does Chevy OBD2 Code P0137 Mean?
The OBD2 code P0137 is a generic powertrain code that can occur in many vehicles, but it’s particularly relevant for Chevy owners. This code signals “Oxygen Sensor Circuit Low Voltage (Bank 1, Sensor 2).” Essentially, your Chevy’s engine control module (ECM) has detected that the voltage from the Bank 1, Sensor 2 oxygen sensor is consistently lower than expected for an extended period.
To break it down further:
- Oxygen Sensor: Oxygen sensors (O2 sensors) are crucial components in your Chevy’s emission control system. They measure the oxygen content in the exhaust gas.
- Bank 1: This refers to the side of the engine where cylinder number 1 is located. In V-type engines (like many in Chevy trucks and SUVs), there are two banks. For inline engines, there’s only Bank 1.
- Sensor 2: This indicates the downstream oxygen sensor. It’s positioned after the catalytic converter in the exhaust system. Sensor 2 monitors the efficiency of the catalytic converter.
- Low Voltage: The sensor is reporting a consistently low voltage signal to the ECM. This is not the normal operating condition and suggests a potential issue.
The P0137 code is very similar to P0136, but specifically points to a low voltage problem. The ECM expects Sensor 2 to have a less active signal than Sensor 1 (upstream sensor), as it’s measuring exhaust after the catalytic converter has done its job. However, persistently low voltage indicates the sensor is not functioning correctly or there’s an issue in the circuit. When the ECM detects this inactive or low voltage state for more than two minutes, it triggers the P0137 code and illuminates the Malfunction Indicator Lamp (MIL), also known as the Check Engine Light on your Chevy’s dashboard.
Symptoms of Chevy Code P0137
Often, the most noticeable symptom of a P0137 code in your Chevy is the illuminated Check Engine Light. However, you might also experience:
- No noticeable symptoms: In some cases, the Check Engine Light may be the only indication of a problem.
- Slight decrease in fuel economy: Although not always significant, an improperly functioning oxygen sensor can affect the engine’s air-fuel mixture, potentially leading to reduced fuel efficiency.
- Possible failed emissions test: Because the oxygen sensor and catalytic converter are vital for emissions control, a P0137 code can cause your Chevy to fail an emissions test.
Common Causes of Chevy P0137 Code
Several factors can trigger a P0137 code in your Chevy. Here are some of the most common causes:
- Faulty Oxygen Sensor (Bank 1, Sensor 2): The most frequent culprit is a failing or failed downstream oxygen sensor itself. Sensors can degrade over time due to heat, contaminants, and general wear.
- Exhaust Leak: An exhaust leak near or before the Bank 1, Sensor 2 O2 sensor can introduce extra oxygen into the exhaust stream. This can skew the sensor readings and cause a low voltage condition.
- Plugged or Failing Catalytic Converter: While Sensor 2 monitors the catalytic converter, a severely plugged or failing converter can sometimes indirectly affect the sensor readings and contribute to a P0137 code.
- Wiring or Connector Issues: Problems in the wiring harness or connector for the Bank 1, Sensor 2 O2 sensor are common causes. This could include:
- Short to Voltage: A wire in the sensor circuit may be shorting to a voltage source, causing incorrect readings.
- High Resistance or Open Circuit: Corrosion, damage, or loose connections can create high resistance or open circuits, disrupting the sensor signal.
- Engine Running Rich or Lean: While less common for P0137, extreme rich or lean fuel conditions can sometimes affect downstream sensor readings. However, these conditions usually trigger other codes first.
- Engine Misfire: A significant engine misfire can introduce unburnt oxygen into the exhaust, potentially affecting the O2 sensor readings. Misfires usually trigger their own specific codes as well.
- Fuel Pressure Issues: Very high or very low fuel pressure can disrupt the air-fuel mixture and potentially contribute to O2 sensor issues, though again, fuel pressure problems often present with other codes first.
Diagnosing and Fixing Chevy P0137
Diagnosing and fixing a P0137 code on your Chevy typically involves a systematic approach:
- OBD-II Code Scan: Use an OBD-II scanner to confirm the P0137 code and check for any other related codes that might provide additional clues.
- Visual Inspection:
- Inspect the O2 sensor: Visually examine the Bank 1, Sensor 2 O2 sensor and its wiring for any obvious damage, loose connections, or corrosion.
- Check for exhaust leaks: Carefully inspect the exhaust system around the sensor for any signs of leaks (soot, hissing sounds).
- Check Sensor Wiring and Circuit:
- Multimeter testing: Use a multimeter to test the O2 sensor circuit for shorts, opens, and proper voltage. Refer to your Chevy repair manual for specific wiring diagrams and testing procedures.
- Inspect the connector: Ensure the O2 sensor connector is clean, secure, and free of corrosion.
- Oxygen Sensor Testing:
- Scanner data: Use a scan tool to monitor the live data stream from the Bank 1, Sensor 2 O2 sensor. Check if the voltage readings are erratic, consistently low, or unresponsive.
- Sensor removal and inspection: If necessary, carefully remove the sensor and inspect it for physical damage or contamination. Note: O2 sensors can be fragile and should be handled with care.
- Catalytic Converter Check: While less likely, if other causes are ruled out, a catalytic converter efficiency test might be considered to check for blockage or failure.
- Address Underlying Issues: If you find evidence of exhaust leaks, wiring problems, or other issues, repair those accordingly.
Possible Solutions:
- Replace the Oxygen Sensor (Bank 1, Sensor 2): If the sensor is determined to be faulty, replacement is usually the most direct solution. Use a high-quality replacement sensor designed for your Chevy model.
- Repair Exhaust Leak: If an exhaust leak is found, repair it professionally. This might involve welding, patching, or replacing exhaust components.
- Repair Wiring or Connector Issues: Repair any shorts, opens, or high resistance in the O2 sensor circuit. Clean or replace corroded connectors.
- Catalytic Converter Replacement: If the catalytic converter is severely restricted or failed, it will need to be replaced. This is a more expensive repair and should only be considered if diagnosed as the root cause.
Important Note: Working on exhaust systems and electrical components requires caution. If you are not comfortable performing these repairs yourself, it is always best to take your Chevy to a qualified mechanic. They will have the specialized tools and expertise to accurately diagnose and repair the P0137 code.
By understanding the meaning, symptoms, causes, and solutions for Chevy Obd2 Code P0137, you can take informed steps to diagnose and resolve the issue, keeping your Chevy running smoothly and efficiently.
