P1134moderate severityPowertrain
HO2S Transition Time Ratio Bank 1 Sensor 1
on 2019 Buick Enclave 3.6L V6 · AWD
What this code means
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.
Other Powertrain codes on this vehicle
P0001
Fuel Volume Regulator Control Circuit/Open
P0002
Fuel Volume Regulator Control Circuit Range/Performance
P0003
Fuel Volume Regulator Control Circuit Low
P0004
Fuel Volume Regulator Control Circuit High
P0010
Intake Camshaft Position Actuator Circuit/Open Bank 1
P0011
Intake Camshaft Position Timing Over-Advanced Bank 1
P0012
Intake Camshaft Position Timing Over-Retarded Bank 1
P0013
Exhaust Camshaft Position Actuator Circuit/Open Bank 1
P0014
Exhaust Camshaft Position Timing Over-Advanced Bank 1
P0015
Exhaust Camshaft Position Timing Over-Retarded Bank 1