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HOMESERVICE MANUALSMAZDA2008CX-7 TOURING, 2.3 3, AWDREPAIR AND DIAGNOSIS (SINGLE PAGE)ENGINE PERFORMANCETESTING & DIAGNOSISON-BOARD DIAGNOSTIC (ENGINE CONTROL SYSTEM) - (3 OF 5)DTC P0403[L3 WITH TC]DIAGNOSTIC PROCEDURE
2008 Mazda CX-7 Touring, 2.3 3, AWD

Diagnostic procedure

2008 Mazda CX-7 Touring, 2.3 3, AWDSECTION Diagnostic procedure
DTC P0403[L3 WITH TC] DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 VERIFY FREEZE FRAME DATA HAS BEEN RECORDED 
  • Has the FREEZE FRAME DATA been recorded?
 Yes Go to the next step.
No Record FREEZE FRAME DATA on the repair order, then go to the next step.
2 VERIFY RELATED REPAIR INFORMATION AVAILABILITY 
  • Check for related Service Bulletins and/or online repair information availability.
  • Is any related repair information available?
 Yes Perform the 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 CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect the 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 ignition switch to the ON position (Engine off).
  • Measure the voltage following the terminal and body ground.
    • EGR valve terminal C (harness-side)
    • EGR valve terminal D (harness-side)
  • Is 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.
6 INSPECT FOR CONTROL CIRCUIT FOR SHORT TO GROUND 
  • Turn the ignition switch off.
  • Inspect for continuity between the following terminals and body ground:
    • EGR valve terminal E (harness-side)
    • EGR valve terminal A (harness-side)
    • EGR valve terminal B (harness-side)
    • EGR valve terminal F (harness-side)
  • is there continuity?
 Yes Repair or replace the wiring harness for a 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 between the following terminals and body ground:
    • EGR valve terminal E (harness-side)
    • EGR valve terminal A (harness-side)
    • EGR valve terminal B (harness-side)
    • EGR valve terminal F (harness-side)
  • Is voltage B+?
 Yes Repair or replace wiring harness for a short to power supply, then go to Step 10.
No Go to the next step.
8 INSPECT PCM CONNECTOR FOR POOR CONNECTION 
  • Turn the ignition switch off.
  • Disconnect 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 PCM connector connected.
  • Inspect for continuity between the following terminals (harness-side):
    • Between EGR valve terminal E and PCM terminal 2AQ
    • Between EGR valve terminal A and PCM terminal 2AM
    • Between EGR valve terminal B and PCM terminal 2AR
    • Between EGR valve terminal F and PCM terminal 2AN
  • Is there continuity?
 Yes Go to the next step.
No Repair or replace harness for 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.
  • Turn the ignition switch off.
  • Start the engine and warm it up completely.
  • Is the PENDING CODE for this DTC present?
 Yes Replace the PCM, then go to the next step. (See PCM REMOVAL/INSTALLATION[L3 WITH TC] ).
No Go to the next step.
11 VERIFY AFTER REPAIR PROCEDURE 
 Yes Go to the applicable DTC inspection. (See DTC TABLE[L3 WITH TC] .)
No Troubleshooting completed.
RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.