What does it mean?
P1162 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Air Fuel Sensor (Bank 1 Sensor 1) Circuit Malfunction .
Symptoms
- Malfunction indicator lamp on with the engine held in open loop
- Higher fuel consumption and noticeably weaker throttle response
- Rough idle and hesitation, especially before the engine is fully warm
- Sulphur smell from the exhaust
- Emissions test failure with incomplete oxygen sensor and catalyst monitors
Likely causes
- Failed wideband sensor element, common after high mileage or a thermal shock
- Open or shorted sensor signal, reference or heater circuit, including a blown heater fuse
- Connector corrosion or water intrusion at the sensor plug
- Pigtail chafed or melted where it runs close to the exhaust manifold
- Sensor poisoned by silicone sealant, coolant leakage into the combustion chamber or excessive oil consumption
- Exhaust leak ahead of the sensor upsetting the measurement
- Failed sensor input or driver circuit inside the PCM (powertrain control module)
How to fix it
- Read the sensor value from a cold start to fully warm and see whether it ever produces a plausible lambda or current reading
- Check the heater fuse and confirm battery voltage on the heater supply at the connector
- Measure heater resistance and compare it with the specified value
- Test the signal and reference circuits for continuity to the PCM and for shorts to ground or voltage
- Inspect the pigtail and connector for heat damage, chafing, corrosion and moisture
- Look for exhaust leaks between the cylinder head and the sensor, and check for oil or coolant consumption that could poison the element
- Fit the correct sensor for that position once the circuit checks good, then confirm closed loop control and stable fuel trims