DTC P2251, P2254 (6-Speed A/T, 16-18 9-Speed A/T)
DTC P2251 : Rear A/F Sensor (Bank 1, Sensor 1) VS Circuit High Voltage
DTC P2254 : Front A/F Sensor (Bank 2, Sensor 1) VS Circuit High Voltage
NOTE:
- Before you troubleshoot, review the general troubleshooting information - Refer to: How to Troubleshoot the Fuel and Emissions Systems .
- If DTC P2251 and/or P2254* is stored at the same time as DTC P0134 and/or P0154*, troubleshoot DTC P2251 and/or P2254* first, then recheck for P0134 and/or P0154*.
- Information marked with an asterisk (*) applies to the front bank (Bank 2).
| DTC Description | Confirmed DTC | Pending DTC | Freeze Frame |
|---|---|---|---|
| P2251 Rear A/F Sensor (Bank 1, Sensor 1) VS Circuit High Voltage | |||
| P2254 Front A/F Sensor (Bank 2, Sensor 1) VS Circuit High Voltage |
DTC (PGM-FI)
- Problem verification
- 1. Turn the vehicle to the ON mode.
- 2. Clear the DTC with the HDS.
- 3. Start the engine.
- 4. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle for 2 minutes.
- 5. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC Freeze Frame P2251 Rear A/F Sensor (Bank 1, Sensor 1) VS Circuit High Voltage P2254 Front A/F Sensor (Bank 2, Sensor 1) VS Circuit High Voltage Is DTC P2251 and/or P2254 * indicated?
YES
The failure is duplicated. Go to step 2.
NO
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the A/F sensor (Sensor 1) and the PCM.
If the freeze data/on-board snapshot of this DTC is recorded, try to reproduce the failure under the same conditions with the freeze data/on-board snapshot - Refer to: How to Troubleshoot the Fuel and Emissions Systems .
- Open wire check (VSB1 (VSB2) * line):
- 1.Turn the vehicle to the OFF (LOCK) mode.
- 2. Jump the SCS line with the HDS, and wait more than 1 minute.
- 3. Disconnect the following connectors.
PCM connector C (51P) A/F sensor (Sensor 1) 6P connector - 4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode PCM connector C (51P): disconnected A/F sensor (Sensor 1) 6P connector: disconnected Test point 1
Rear A/F sensor (Bank 1, Sensor 1) 6P connector No. 6 Front A/F sensor (Bank 2, Sensor 1) 6P connector No. 6 * Test point 2
PCM connector C (51P) No. 25 - Refer to:
PCM Connector for Inputs and Outputs (16-20 6-Speed A/T), or
PCM Connector for Inputs and Outputs (16-18 9-Speed A/T)PCM connector C (51P) No. 28* - Refer to:
PCM Connector for Inputs and Outputs (16-20 6-Speed A/T), or
PCM Connector for Inputs and Outputs (16-18 9-Speed A/T)Is there continuity?
YES
The VSB1 (VSB2) * wire is OK. Go to step 3.
NO
Repair an open in the VSB1 (VSB2) * wire between the PCM (C25 (C28) *) and the A/F sensor (Sensor 1).
- PCM internal circuit check
- 1. Reconnect the following connector.
PCM connector C (51P) - 2. Exit the SCS mode with the HDS.
- 3. Start the engine.
- 4. Hold the engine speed at 3, 000 rpm without load (in P or N) until the radiator fan comes on, then let it idle for 2 minutes.
- 5. Measure the voltage between test points 1 and 2.
Test condition
Engine running A/F sensor (Sensor 1) 6P connector: disconnected Test point 1
Rear A/F sensor (Bank 1, Sensor 1) 6P connector No. 6 Front A/F sensor (Bank 2, Sensor 1) 6P connector No. 6 * Test point 2 Body ground Is there about 0.2 V or less?
YES
Check for any authorized service information related to the DTCs or symptoms you are troubleshooting or substitute a known-good PCM - Refer to:
PCM Removal and Installation (6-Speed A/T, 16-18 9-Speed A/T) .
NO
The PCM internal circuit is OK. Replace the A/F sensor (Sensor 1) .