What does it mean?
P1134 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: HO2S-11 (Bank 1 Sensor 1) Transition Time Ratio Error .
Symptoms
- Malfunction indicator lamp on with normal or near-normal driveability
- Fuel trims drifting further from zero over time
- Small stumble at steady cruise or during light throttle changes
- Increased fuel consumption noticed over a tank
- Readiness monitors remaining incomplete after a drive cycle
Likely causes
- Sensor element slowed unevenly by age, so one transition direction lags the other
- Silicone, phosphorus or coolant contamination coating the sensing tip
- Exhaust leak near the sensor letting air in only under certain load conditions
- Heater not fully effective, so the element cools during long idle periods
- Signal circuit resistance or a poor sensor ground rounding off the waveform
- Injector fouling or a leaking injector causing an uneven mixture pulse at that bank
- Intake air leak that appears only at idle or only under vacuum
How to fix it
- Record a high resolution graph of the sensor voltage and measure the rise and fall times separately
- Use propane enrichment and a controlled air leak to force each direction and time the response
- Compare the Bank 1 sensor waveform with the opposite bank if the engine has two banks
- Check for exhaust leaks under load, not just at idle, using a smoke machine on the exhaust
- Confirm heater supply, heater resistance and the sensor ground quality
- Inspect injector spray quality or run an injector balance test if trims are skewed
- Fit a correct specification sensor once wiring and exhaust check good, then re-run the monitor