The signal from the lambda probe after the catalytic converter is out of the ordinary - no voltage, constantly high or unresponsive.
Low. The rear probe monitors the catalyst and has almost no effect on the mixture. The car drives normally, but it won't pass the emissions test.
Gasoline engines. Rear lambda probe, wiring, exhaust.
What does P0136 mean
"Bank 1" is the side of the engine with the first cylinder, and "probe 2" is the one after the catalytic converter. She checks that the catalytic converter is working. If its signal is incorrect, the computer cannot evaluate the catalyst and sometimes writes P0136 instead P0420. A fault in the heater of the same probe is P0141.
Symptoms
- Lamp "Check Engine"
- There is usually no change in ride
- Sometimes a slightly increased cost
- Failed emissions technical review
| Can it be driven?
Yes. Fix the problem before the inspection and before changing the catalytic converter - often only the probe is to blame.
Common reasons
- Outdated or dirty probe — normal after a long run.
- Damaged cable or oxidized coupling — the probe is low under the car and exposed to water and salt.
- Exhaust leak in front of the probe — aspirated air distorts the signal.
- Short circuit between the heater and the signal wire.
How we diagnose it
- We look at the signal of the front and rear probe when the engine is warm.
- We check the wiring and the clutch under the car.
- We are looking for leaks in the exhaust around the probe.
- We change the probe only if the circuit is fine.