For 1990-2009 cars

Insert Graphic SMSCM90895AA

The heated oxygen sensor (HO2S) bank 2 sensor 1 is threaded into the cylinder 2, 4, 6 exhaust manifold (cylinders 2, 4, 6 are closest to front of radiator). The sensor monitors the oxygen content in the exhaust gas before the pre-converter. The ECM supplies a variable output pump current to circuit 1664 in order to maintain a constant voltage level at the input pump current circuit 1666. As output pump current passes through the oxygen sensor when the sensor is operating above 300°C (572°F), the sensor will vary resistance according to changes in exhaust oxygen content. If oxygen content increases (lean air/fuel ratio) the resistance of the sensor increases, which requires less current to maintain a constant voltage level. The ECM calculates a lambda value (actual air/fuel ratio divided by 14.7 to 1) based on the input pump current voltage level on circuit 1666 and the signal voltage level on circuit 1653. DTC P0153 will set if the ECM determines that the HO2S bank 2 sensor 1 response times for changing air/fuel ratios are becoming too long. The ECM compares the actual response times to modeled response times, then assigns a quality factor to the comparison. Once the quality factor drops below a calibrated threshold, DTC P0153 will set indicating the HO2S bank 2 sensor 1 is responding too slowly.

### DTC Parameters

DTC P0153 will set if the ECM comparison quality factor for the HO2S bank 2 sensor 1 response test is below 60% indicating a slow responding sensor when:

• | Engine speed is between 1400 and 2520 rpm

• | Engine load is between 23 and 45%

• | HO2S bank 2 sensor 1 lambda value is between 0.96 and 1.04

• | No EVAP purge solenoid, EVAP system, fuel trim or misfire DTCs have been set

DTC P0153 diagnostic runs continuously once the above conditions have been met.

P0153 is a type B DTC.

### Diagnostic Aids

Make sure no corrosion is present in the HO2S bank 2 sensor 1 harness connector. Make sure no exhaust leaks exist between the bank 2 engine head and HO2S bank 2 sensor 2. Each of these two conditions may set P0153.

The most probable cause for DTC P0153 is a weak, aging or contaminated sensor. Check for obvious contamination (oil, fuel or engine coolant) by removing sensor. Source and fix the cause of the contamination if contaminated. Replace the HO2S bank 2 sensor 1.

Bank 2 will default to open loop if this DTC is active.