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2008 - MX-5 - Engine

DTC P0403 [LF]



DTC P0403

EGR valve (stepping motor) circuit problem

DETECTION CONDITION

  • The PCM monitors the EGR valve control signal voltage and current. If the following conditions are met, the PCM determines that there is the EGR control circuit problem.

    • The PCM turns the EGR valve off, but the voltage of the EGR valve control signal remains low.

    • The PCM turns the EGR valve on, but the current of the EGR valve control signal remains high.

    Diagnostic support note
  • This is a continuous monitor (CCM).

  • The MIL illuminates if the PCM detects the above malfunction conditions 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 condition during the first drive cycle.

  • FREEZE FRAME DATA is available.

  • The DTC is stored in the PCM memory.

POSSIBLE CAUSE

  • EGR valve malfunction

  • Connector or terminal malfunction

  • Short to power supply in wiring harness between EGR valve terminal E and PCM terminal 2K

  • Short to power supply in wiring harness between EGR valve terminal A and PCM terminal 2G

  • Short to power supply in wiring harness between EGR valve terminal B and PCM terminal 2L

  • Short to power supply in wiring harness between EGR valve terminal F and PCM terminal 2H

  • Short to ground circuit in wiring harness between EGR valve terminal E and PCM terminal 2K

  • Short to ground circuit in wiring harness between EGR valve terminal A and PCM terminal 2G

  • Short to ground circuit in wiring harness between EGR valve terminal B and PCM terminal 2L

  • Short to ground circuit in wiring harness between EGR valve terminal F and PCM terminal 2H

  • Open circuit in wiring harness between EGR valve terminal E and PCM terminal 2K

  • Open circuit in wiring harness between EGR valve terminal A and PCM terminal 2G

  • Open circuit in wiring harness between EGR valve terminal B and PCM terminal 2L

  • Open circuit in wiring harness between EGR valve terminal F and PCM terminal 2H

  • Open circuit in wiring harness between main relay and EGR valve terminal C

  • Open circuit in wiring harness between main relay and EGR valve terminal D

  • PCM malfunction


Diagnostic procedure

STEP

INSPECTION

ACTION

1

VERIFY FREEZE FRAME DATA 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 REPAIR INFORMATION AVAILABILITY
  • Verify related Service Bulletins and/or on-line repair information availability.

  • Is any related repair information available?

Yes

Perform repair or diagnosis according to the available repair information.

  • If the vehicle is not repaired, go to the next step.

No

Go to the next step.

3

INSPECT EGR VALVE FOR POOR CONNECTION
  • Turn the ignition switch off.

  • Disconnect EGR valve connector.

  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).

  • Is there any malfunction?

Yes

Repair or replace the terminals and/or connector, then go to Step 10.

No

Go to the next step.

4

INSPECT POWER CIRCUIT FOR OPEN CIRCUIT
  • Turn the ignition switch to the ON position (Engine off).

  • Measure the voltage following terminal and body ground.

    • EGR valve terminal C

    • EGR valve terminal D

  • Is the voltage B+?

Yes

Go to the next step.

No

Repair or replace the wiring harness for an open circuit then go to Step 10.

5

INSPECT EGR VALVE

Yes

Go to the next step.

No

Replace the EGR valve, then go to Step 10.

(See EGR VALVE REMOVAL/INSTALLATION [LF].)

6

INSPECT FOR CONTROL CIRCUIT FOR SHORT TO GROUND
  • Turn the ignition switch off.

  • Inspect for continuity between the following terminal and body ground:

    • EGR valve terminal E

    • EGR valve terminal A

    • EGR valve terminal B

    • EGR valve terminal F

  • is there continuity?

Yes

Repair or replace the wiring harness for short to ground, then go to Step 10.

No

Go to the next step.

7

INSPECT FOR CONTROL CIRCUIT FOR SHORT TO POWER SUPPLY
  • Turn the ignition switch to the ON position (Engine off).

  • Measure the voltage following terminal and body ground:

    • EGR valve terminal E

    • EGR valve terminal A

    • EGR valve terminal B

    • EGR valve terminal F

  • Is the voltage B+?

Yes

Repair or replace the wiring harness for short to power supply, then go to Step 10.

No

Go to the next step.

8

INSPECT PCM FOR POOR CONNECTION
  • Turn the ignition switch off.

  • Disconnect the PCM connector.

  • Inspect for poor connection (such as damaged/pulled-out pins, corrosion).

  • Is there any malfunction?

Yes

Repair or replace the terminals and/or connector, then go to Step 10.

No

Go to the next step.

9

INSPECT CONTROL CIRCUIT FOR OPEN CIRCUIT
  • Remove the PCM with the PCM connector connected.

  • Inspect for continuity following terminals:

    • Between EGR valve terminal E and PCM terminal 2K

    • Between EGR valve terminal A and PCM terminal 2G

    • Between EGR valve terminal B and PCM terminal 2L

    • Between EGR valve terminal F and PCM terminal 2H

  • Is there continuity?

Yes

Go to the next step.

No

Repair or replace the wiring harness for an open circuit then go to the next step.

10

VERIFY TROUBLESHOOTING OF DTC P0403 COMPLETED
  • Make sure to reconnect all disconnected connectors.

  • Clear the DTC from the PCM memory using the M-MDS.

  • Start the engine.

  • Is the PENDING CODE for this DTC present?

Yes

Replace the PCM, then go to the next step.

(See PCM REMOVAL/INSTALLATION [LF].)

No

Go to the next step.

11

VERIFY AFTER REPAIR PROCEDURE

Yes

Go to the applicable DTC troubleshooting.

(See DTC TABLE [LF].)

No

Troubleshooting completed.




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