DTC P2251 [L3 Turbo]

id0102b7813400

DTC P2251

A/F sensor negative current control circuit open
DETECTION CONDITION
•  The PCM monitors the A/F sensor negative current control circuit voltage. If the voltage does not change with the PCM control value while the engine is running, the PCM determines that the A/F sensor negative current control circuit is open.
Diagnostic support note
•  This is a continuous monitor. (A/F sensor, HO2S)
•  MIL illuminates if the PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
•  PENDING CODE is available if the PCM detects the above malfunction conditions during the first drive cycle.
•  FREEZE FRAME DATA is available.
•  DTCs are stored in the PCM memory.
POSSIBLE CAUSE
•  A/F sensor malfunction
•  Connector or terminal malfunction
•  Open circuit between PCM terminal 2AC and A/F sensor terminal 1B
•  A/F sensor heater cannot be controlled
•  PCM malfunction

Diagnostic procedure

STEP

INSPECTION

ACTION
1
VERIFY FREEZE FRAME DATA AND DIAGNOSTIC MONITORING TEST RESULTS HAS BEEN RECORDED
•  Has FREEZE FRAME DATA been recorded?
Yes
Go to the next step.
No
Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2
VERIFY RELATED SERVICE INFORMATION AVAILABILITY
•  Verify related Service Information availability.
•  Is any related Service Information available?
Yes
Perform the repair or diagnosis according to the available Service Information.
•  If the vehicle is not repaired, go to the next step.
No
Go to the next step.
3
VERIFY RELATED PENDING CODE OR STORED DTC
•  Turn the ignition switch to off, then ON position (Engine off).
•  Verify the related PENDING CODE or stored DTCs using the M-MDS.
•  Is the DTC P0030, P0031 or P0032 also present?
Yes
Go to appropriate DTC troubleshooting procedure.
(See DTC TABLE [L3 Turbo].)
No
Go to the next step.
4
IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA
•  Is DTC P2251 on FREEZE FRAME DATA?
Yes
Go to the next step.
No
Go to troubleshooting for DTC on FREEZE FRAME DATA.
(See DTC TABLE [L3 Turbo].)
5
INSPECT A/F SENSOR CONNECTOR FOR POOR CONNECTION
•  Turn the ignition switch to off.
•  Disconnect the A/F sensor connector.
•  Inspect for poor connection (such as damaged/ pulled-out pins, and corrosion).
•  Is there any malfunction?
Yes
Repair or replace the terminal, then go to Step 8.
No
Go to the next step.
6
INSPECT PCM CONNECTOR FOR POOR CONNECTION
•  Turn the ignition switch to off.
•  Disconnect the PCM connector.
•  Inspect for poor connection (such as damaged/ pulled-out pins, and corrosion).
•  Is there any malfunction?
Yes
Repair or replace the terminal, then go to Step 8.
No
Go to the next step.
7
INSPECT A/F SENSOR NEGATIVE CURRENT CONTROL CIRCUIT FOR OPEN AT PCM - A/F SENSOR
•  The A/F sensor and the PCM connectors disconnected.
•  Verify the continuity between the PCM terminal 2AC and the A/F sensor terminal 1B at harness-side connectors.
•  Is there continuity?
Yes
Replace the A/F sensor, then go to the next step.
No
Repair or replace for open circuit, then go to the next step.
8
VERIFY TROUBLESHOOTING OF DTC P2251 COMPLETED
•  Make sure to reconnect all disconnected connectors.
•  Clear the DTC from the PCM memory using the M-MDS.
•  Perform the KOEO or KOER self-test using the M-MDS.
•  Is the PENDING CODE same DTC present?
Yes
Replace the PCM, then go to the next step.
(See PCM REMOVAL/INSTALLATION [L3 Turbo].)
No
Go to the next step.
9
VERIFY AFTER REPAIR PROCEDURE
•  Perform the "After Repair Procedure".
•  Are any DTCs present?
Yes
Go to the applicable DTC inspection.
(See DTC TABLE [L3 Turbo].)
No
Troubleshooting completed.