What does it mean?
P1163 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Air Fuel Sensor (Bank 1 Sensor 1) Slow Response .
Symptoms
- Check engine light on with the code stored
- Uneven idle and slight hesitation when accelerating
- Higher fuel consumption than usual
- Engine takes longer than normal to enter closed loop after a cold start
- Fuel smell from the exhaust or a failed emissions test
- Catalyst efficiency codes may follow if the fault is left unrepaired
Likely causes
- Aged sensing element that can no longer follow rapid mixture changes
- Element contaminated by burnt oil, coolant or silicone sealant vapour from an internal leak
- Exhaust leak at the manifold, flange or sensor bung ahead of the sensor, diluting the sample with outside air
- High resistance, corroded pins or a spread terminal in the sensor connector or harness
- Weak heater circuit, so the element never reaches operating temperature and reacts sluggishly
- Persistent fuel pressure or vacuum leak problems that keep the mixture drifting and make the sensor look lazy
- Rarely, a failing PCM (powertrain control module) sensor drive circuit
How to fix it
- Read freeze frame data and note load, coolant temperature and fuel trims at the moment the code set
- Graph the sensor current/voltage on a scan tool during a snap-throttle test and compare it with the other bank
- Inspect the connector and harness for corrosion, oil soaking, melted insulation or chafing against the exhaust; wiggle-test while watching live data
- Check the exhaust upstream of the sensor for leaks at the manifold, gasket and bung
- Measure heater supply voltage and heater element resistance, and check the related fuse
- Verify fuel pressure and look for unmetered air leaks that keep long term fuel trim skewed
- Replace the air/fuel sensor with the correct part only after slow response is confirmed, then clear codes and recheck trims on a road test