P0136 O2 Sensor Circuit Bank 1 Sensor 2

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.

Likely causes

Symptoms

• Check engine light on (usually after two drive cycles)
• Catalyst monitor readiness not set
• Slightly higher consumption possible without downstream trim

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

What to check first

1. Inspect wiring routed near the exhaust
2. Check for exhaust leaks
3. Watch sensor voltage switching on a scan tool

Parts involved

Related codes

References: law.cornell.edu, newtonnet.co.uk, fordservicecontent.com, saabwisonline.com.