The oxygen sensor after the catalytic converter on bank 1 (sensor 2) is a switching sensor (about 0.1–0.9 V) used for converter monitoring and fine mixture trim. P0136 is the general circuit code, and its exact meaning varies by manufacturer. Ford sets it as 'no activity' in a functional check: if the sensor never swings beyond about 0.42/0.48 V despite rich and lean phases – if needed after forced enrichment and leaning – once per drive cycle. Opel/GM Europe set it if the average voltage stays outside 400–500 mV after 10 min of closed loop; older Bosch Motronic if it stays at 0 V for 200 s despite heating. GM North America does not use P0136. When it fails, the control module stops the downstream trim and cannot evaluate the converter; there is no limp mode.
Low severity. Can I keep driving?You can keep using the car normally in the short term, because the engine regulates the mixture with the front sensor. However, you will not know how the catalytic converter is doing until it is repaired, and you could have trouble at an emissions inspection.
Bank 1 is the side of the engine with cylinder 1. Inline engines only have this bank. Sensor 2 is the sensor after the catalytic converter.
Symptoms
- Check engine light on (usually after two drive cycles)
- Catalyst monitor readiness not set
- Slightly higher consumption possible without downstream trim
Most likely causes
- Downstream sensor aged or poisoned (stays in the middle band)
- Signal or ground wire open or high-resistance, connector corroded
- Sensor heater failed (sensor stays cold)
- Exhaust leak ahead of the sensor
- Control module or software
What to check, in order
Start with the simplest. You can tick off each step.
Good to know
- Repair difficulty: easy
- It affects emissions.
What each character of P0136 means
- P: Powertrain: engine and transmission
- 0: Generic code: same on every make
- 1: Air and fuel
- 36: Specific fault in that system
Frequently asked questions
Can I keep driving with code P0136?
You can keep using the car normally in the short term, because the engine regulates the mixture with the front sensor. However, you will not know how the catalytic converter is doing until it is repaired, and you could have trouble at an emissions inspection.
What causes code P0136?
The most common causes are: downstream sensor aged or poisoned (stays in the middle band); signal or ground wire open or high-resistance, connector corroded; sensor heater failed (sensor stays cold).
Related codes
- P0137O2 Sensor Circuit Low Voltage Bank 1 Sensor 2
- P0138O2 Sensor Circuit High Voltage Bank 1 Sensor 2
- P0140O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2
- P0141O2 Sensor Heater Circuit Bank 1 Sensor 2
- P0156O2 Sensor Circuit Bank 2 Sensor 2
- P2270O2 Sensor Signal Biased/Stuck Lean (Bank 1, Sensor 2)
Sources
- law.cornell.edu: 13 CCR 1968.2
- newtonnet.co.uk: fordobd2012
- fordservicecontent.com: OBD Operations Summary Gasoline 2020 2023
- saabwisonline.com: dtc p0136 llu
Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.