P0136
O2 Sensor Circuit Bank 1 Sensor 2
Oxygen sensor (O2)
Generic OBD-II
Medium
What it means
P0136 means the engine computer has detected a circuit problem with the downstream oxygen sensor (bank 1, sensor 2), located after the catalytic converter. This sensor monitors converter efficiency rather than controlling fuel, so the car usually drives normally — but the code keeps the check-engine light on and can block emissions readiness.
Medium
Can I keep driving? Yes — a rear O2 sensor fault doesn't usually affect driving; fix it to clear the light and let emissions monitors complete.
Common symptoms
What you'll notice
- Check-engine light on
- Emissions readiness monitor won't complete or fails an emissions test
- Occasionally a slight change in fuel economy
Common causes
Most likely first
- Failed or aged downstream oxygen sensor (bank 1, sensor 2)Likely
- Wiring or connector fault at the sensor (heat or corrosion damage)Common
- Exhaust leak near the sensorCommon
- Failed ECM (rare)Less often
How to diagnose & fix
Work through it in order
- Read the sensor 2 live signal to confirm it is inactive or out of range.
- Inspect the sensor's wiring and connector, and check the exhaust for leaks near the sensor.
- Check the sensor heater circuit if the signal never warms up.
- Replace the downstream O2 sensor if it has failed.
- Only consider the ECM after wiring and sensor checks pass.
FAQ
Quick answers
Is it safe to drive with P0136?+
Yes. The rear O2 sensor monitors catalytic-converter efficiency rather than controlling fuel, so driving is normally unaffected. The main issue is the check-engine light and blocked emissions readiness.
Can I just clear P0136?+
It will return once the ECM re-checks the sensor. The sensor or its wiring needs repair to keep the code from coming back.
Related codes
Often seen with P0136
Read & clear P0136 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX