P1154moderate severityPowertrain
HO2S Transition Time Ratio Bank 2 Sensor 1
on 2004 Cadillac STS 4.6L V8 · RWD
What this code means
The PCM detected an abnormal transition time ratio for the upstream O2 sensor on Bank 2. The sensor is transitioning faster in one direction than the other.
Symptoms
- Check Engine Light
- Poor fuel economy
- Failed emissions test
- Subtle performance loss
Common causes
- Degraded O2 sensor Bank 2
- Exhaust leak near sensor
- Fuel system imbalance
- Contaminated sensor
Diagnostic steps
- Monitor O2 sensor waveform
- Check for exhaust leaks
- Test fuel trim values
- Inspect sensor for contamination
Repair notes
Replace upstream O2 sensor Bank 2. Often appears with P1153.
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