HO2S Transition Time Ratio Bank 1 Sensor 1
2002-2009 GMC Envoy 4.2L I6
Description
The PCM detected that the upstream O2 sensor on Bank 1 has an abnormal rich-to-lean vs lean-to-rich transition time ratio. The time the sensor takes to switch in one direction is significantly different from the other, indicating sensor degradation.
Symptoms
- Check Engine Light
- Poor fuel economy
- Rough running
- Failed emissions test
- Subtle performance loss
Common Causes
- Degraded or aging O2 sensor
- Exhaust leak near sensor
- Fuel system imbalance
- Contaminated O2 sensor (coolant or oil)
Diagnostic Steps
- Monitor O2 sensor waveform for asymmetric transitions
- Check for exhaust leaks
- Test fuel pressure and trim values
- Inspect sensor for contamination
Repair Notes
Replace upstream O2 sensor Bank 1. Often appears alongside P1133.
Related Codes
Other Powertrain Codes
- P0001Fuel Volume Regulator Control Circuit/Open
- P0001Fuel Volume Regulator Control Circuit/Open
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0002Fuel Volume Regulator Control Circuit Range/Performance
- P0003Fuel Volume Regulator Control Circuit Low
- P0003Fuel Volume Regulator Control Circuit Low
- P0004Fuel Volume Regulator Control Circuit High
- P0004Fuel Volume Regulator Control Circuit High
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
- P0010Intake Camshaft Position Actuator Circuit/Open Bank 1
P1134 on Other Vehicles
Common Questions
What does code P1134 mean on a 2002-2009 GMC Envoy?
P1134 stands for "HO2S Transition Time Ratio Bank 1 Sensor 1". The PCM detected that the upstream O2 sensor on Bank 1 has an abnormal rich-to-lean vs lean-to-rich transition time ratio. The time the sensor takes to switch in one direction is significantly different from the other, indicating sensor degradation.
What are the symptoms of P1134 on a GMC Envoy?
Common symptoms of P1134 include: Check Engine Light, Poor fuel economy, Rough running, Failed emissions test, Subtle performance loss.
What causes P1134 on a 2002-2009 GMC Envoy?
Common causes of P1134 include: Degraded or aging O2 sensor, Exhaust leak near sensor, Fuel system imbalance, Contaminated O2 sensor (coolant or oil).