P0153
O2 Sensor Circuit Slow Response Bank 2 Sensor 1.
- Generic
- Powertrain
- Generic code
- Low severity
How this code is built
- P
- SystemPowertrain
- 0
- Defined bySAE, the same on every car
- 1
- AreaFuel and air metering
- 53
- FaultThe specific fault in that area
What it means
P0153 means the upstream oxygen sensor (Bank 2, Sensor 1) is switching between rich and lean more slowly than the control unit expects. The control unit monitors the sensor's switching rate and response time during closed-loop running, and it set the code when the response fell outside its limit. Bank 2 is the side of the engine that does not contain cylinder number one.
Symptoms
- Engine management light on
- Slightly higher fuel consumption
- Rough or unstable idle
- Hesitation or reduced performance under load
- Failed emissions test
- Possible fuel smell or black smoke from the exhaust on that bank
Possible causes
- Aged or contaminated Bank 2 Sensor 1 oxygen sensor (slow response from wear, carbon, oil, coolant or silicone contamination)likely
- Exhaust leak upstream of or near the sensor, letting in false airpossible
- Damaged wiring, poor connector contact or corroded terminals in the sensor circuit or heater feedpossible
- Fuel mixture problem on Bank 2, such as a vacuum leak, leaking or blocked injector, or incorrect fuel pressurepossible
- Engine misfire or oil or coolant burning on Bank 2 contaminating the sensorpossible
- Fault in the control unit sensor input or an outdated calibration (model specific)rare
How to diagnose
- Read all stored and pending codes and note the freeze frame data, including engine load, coolant temperature and fuel trims, then check for related misfire or fuel trim codes.
- Confirm which side is Bank 2 for this engine, and which sensor is Sensor 1 (upstream), using the manufacturer's data.
- Visually inspect the sensor, wiring and connector for heat damage, chafing, oil or coolant contamination and corrosion.
- Check for exhaust leaks around the manifold, flexible joints and sensor mounting point, and for vacuum or intake leaks on Bank 2.
- Review short and long term fuel trims for Bank 2 at idle and at 2,500 rpm to spot a mixture problem behind the slow response.
- Using a scan tool or oscilloscope, watch the sensor live data and check its switching speed and voltage range at operating temperature against the manufacturer's specification.
- Check the sensor heater circuit supply, earth and resistance as per the manufacturer's procedure.
- Check for misfires and for signs of oil or coolant consumption that could contaminate the sensor.
How to fix
- Replace the Bank 2 upstream oxygen sensor if it is slow, aged or contaminated, and fix any source of contamination first.
- Repair or replace any damaged wiring, connectors or terminals in the sensor circuit.
- Repair exhaust leaks near the sensor, and renew faulty gaskets or joints.
- Correct vacuum leaks, injector faults or fuel pressure issues causing the mixture error on Bank 2.
- Repair the cause of any misfire or oil or coolant consumption before fitting a new sensor.
- Apply a manufacturer calibration update only where the manufacturer lists an outdated calibration as a known cause for this model.
Can I keep driving?
Low severity
The car can normally be driven for a short time while you book a repair. Do not leave it for long, as poor mixture control can raise fuel use and emissions and may eventually harm the catalytic converter.
Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.