Draft guidance: awaiting Claude spot-check, qualified-mechanic review and named-editor approval. Do not use a fault code alone to replace parts.
P0136: Oxygen sensor circuit malfunction, Bank 1 Sensor 2
The computer has detected a general signal or circuit fault for the downstream Bank 1 sensor, normally after the catalytic converter.
What P0136 means
The computer has detected a general signal or circuit fault for the downstream Bank 1 sensor, normally after the catalytic converter. This sensor is mainly used to monitor catalyst operation, so P0136 alone often has less effect on driving than an upstream-sensor fault.
Can I still drive?
A short period of careful use is usually reasonable when the light is steady and the vehicle runs normally, but arrange diagnosis because catalyst monitoring is compromised. Severe roughness, stalling or major power loss is unusual for this code alone and suggests another fault that may justify stopping.
Symptoms
- Engine-management light as the only symptom
- Failed emissions or readiness test
- Possible reduced economy, roughness or unusual exhaust smell when another fault is present
Common causes
- Failed or contaminated downstream sensor
- Heat-damaged wiring or loose, wet or corroded connector
- Open or shorted signal circuit
- Exhaust leak near or ahead of the sensor
- Related heater fault, sometimes accompanied by P0141
Safe first checks
- Record codes and freeze-frame data. Once the exhaust is fully cold, inspect the downstream lead and plug, which face both exhaust heat and road contamination. Look for soot around joints that may indicate a leak. A technician can compare upstream and downstream traces, but P0136 alone is not evidence that the catalytic converter must be replaced.
Typical UK fix cost
About £90–£350 for diagnosis and a common circuit, leak or sensor repair. A straightforward lambda replacement is often £110–£266; damaged exhaust fittings, seized sensors or loom repair can push the bill higher.
Related models
This is a generic OBD-II code used across many makes and models. The exact test thresholds, component layout and repair route vary by engine and manufacturer, so check vehicle-specific technical information before ordering parts.
Related fault codes
- P0134: Oxygen sensor circuit no activity detected, Bank 1 Sensor 1
- P0135: Oxygen sensor heater circuit malfunction, Bank 1 Sensor 1
- P0137: Oxygen sensor circuit low voltage, Bank 1 Sensor 2
- P0138: Oxygen sensor circuit high voltage, Bank 1 Sensor 2
Sources
A diagnostic trouble code identifies a system or circuit to investigate. It does not prove that a named part has failed. Preserve freeze-frame data and seek a vehicle-specific diagnosis before clearing the code.