What does it mean?
P1158 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Lack Of HO2S22 Switches - Sensor Indicates Rich .
Symptoms
- Malfunction indicator lamp on with a rich fuel smell from the exhaust
- Poor fuel economy and sooty deposits at the tailpipe on that side
- Rough idle and slight loss of power
- Fuel trims sitting strongly negative on Bank 2
- Catalyst monitor failing to complete after a full drive cycle
Likely causes
- Genuinely rich exhaust reaching the rear sensor from leaking injectors or excessive fuel pressure
- Contaminated or aged rear sensor biased high and no longer responding
- Evaporative purge valve stuck open, adding fuel vapour continuously
- High resistance in the rear sensor ground circuit, lifting the measured voltage
- Signal wire shorted to another circuit carrying voltage
- Catalytic converter no longer storing oxygen, so the rear signal mirrors the front sensor
- Restricted air filter or intake duct making the mixture rich on that bank
How to fix it
- Graph the Bank 2 rear sensor together with the front sensor and the fuel trims to see whether the mixture is genuinely rich
- Snap the throttle and watch whether the rear signal moves at all; a completely flat high signal points at the sensor or its circuit
- Check fuel pressure and test for a leaking injector on that bank
- Verify the purge valve seals with the engine off and check purge duty in live data
- Measure the rear sensor ground circuit voltage drop and inspect the connector for corrosion
- Check the signal wire for a short to a powered circuit with the sensor disconnected
- Replace the rear sensor once the rich condition and wiring are ruled out, then confirm the monitor completes