P0153 — O2 Sensor Circuit Slow Response (Bank 2, Sensor 1)
Low severityWhat it means
P0153 is stored when the engine control unit sees a fault involving the upstream oxygen sensor on bank 2 (sensor 1). On V-type engines, bank 2 is the cylinder bank opposite cylinder 1; this upstream sensor trims fuel for that bank before the converter. “Slow response” means the oxygen sensor still works but switches between rich and lean too slowly — a classic sign of an aged sensor.
Common symptoms
- Slightly higher fuel use or a failed emissions test
- Rough running or higher fuel use
- Check engine light
- Failed emissions test
Likely causes
- Aged or contaminated oxygen sensor
- Silicone or oil contamination on the sensor tip
- Aged or contaminated bank 2 oxygen sensor
- An exhaust leak near the sensor
What to check first
- Watch the sensor's switching speed in live data and compare with a healthy sensor
- Compare bank 1 and bank 2 sensor behaviour in live data
- Inspect the bank 2 exhaust and sensor wiring
Can you keep driving?
Drivable short-term; like any fuel-control sensor it wastes fuel and stresses the converter, so repair soon.
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