Diagnostic Instructions
DTC Descriptors
DTC P2232: HO2S Signal Circuit Shorted to Heater Circuit Bank 1 Sensor 2
DTC P2235: HO2S Signal Circuit Shorted to Heater Circuit Bank 2 Sensor 2
Circuit Description
The engine control module (ECM) supplies a voltage near 450 mV between the heated oxygen sensor (HO2S) signal circuit and the low reference circuit. The HO2S varies the voltage over a range from about 1,000 mV when the exhaust is rich, down
through about 10 mV when the exhaust is lean. The ECM monitors and stores the HO2S voltage information. The ECM evaluates the HO2S voltage samples in order to determine the amount of time that the HO2S voltage was out of range. Or, to detect if the HO2S
signal voltage switches at the same rate at which the ECM is commanding the heater ON and OFF.
Conditions for Running the DTC
| • | The engine is operating. |
| • | The ignition voltage is greater than 10 volts. |
| • | The calculated exhaust gas temperature is between 250-800°C (482-1,472°F) for greater than 90 seconds. |
| • | The HO2S heater control is enabled for greater than 10 seconds. |
| • | DTC P2232 and P2235 run continuously once the conditions above exist for greater than 10 seconds. |
Conditions for Setting the DTC
| • | The ECM detects that the HO2S signal voltage increases greater than 2 volts within 0.04 second, in 4 out of 6 HO2S heater switch OFF samples. |
| • | The condition exists for greater than 4 seconds, or for a cumulative of 30 seconds. |
Action Taken when the DTC Sets
DTCs P2232 and P2235 are Type B DTCs.
Conditions for Clearing the MIL/DTC
DTCs P2232 and P2235 are Type B DTCs.
Diagnostic Aids
| • | The HO2S voltage should be between 350-550 mV with the ignition ON. If the voltage is greater than the specified value, there is a condition with the HO2S circuits. If the voltage does not change after disconnecting the HO2S, the condition
is between the sensor and the ECM. If the voltage is between 350-550 mV after disconnecting the sensor, the condition is with the HO2S. |
| • | Inspect the HO2S harness connector for water intrusion. Moisture in a connector may cause voltage to bleed to other circuits within the connector. |
Reference Information
Schematic Reference
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information
Circuit/System Verification
- Ignition ON, observe the appropriate HO2S voltage parameter. The HO2S voltage parameter should be less than 1,050 mV.
- Operate the vehicle within the Conditions for Running the DTC to verify the DTC does not reset. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
- Ignition OFF, disconnect the harness connector at the appropriate HO2S.
- Ignition ON, verify that the HO2S parameter is between 350-500 mV.
| ⇒ | If greater than 500 mV, test the signal circuit of the HO2S sensor for a short to the heater circuit. If the circuit/connections test normal, replace the ECM. |
- If all circuits/connections test normal, replace the applicable HO2S.
Repair Instructions
Perform the
Diagnostic Repair Verification after completing the diagnostic procedure.
