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

1. Monitor O2 sensor waveform
2. Check for exhaust leaks
3. Test fuel trim values
4. Inspect sensor for contamination

Repair notes

Replace upstream O2 sensor Bank 2. Often appears with P1153.

Other Powertrain codes on this vehicle