LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Mazda >> 2007 >> 6 i, 4D Hatchback, Standard >> Repair and Diagnosis >> Engine Performance >> System >> Symptom Troubleshooting [Engine Control System L3) >> No. 17 Cooling System Concerns-Overheating >> Diagnostic procedure
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diagnostic procedure

DIAGNOSTIC PROCEDURE

STEP INSPECTION ACTION
1 Inspect the following:
  • Engine coolant level
  • Coolant leakage
  • Water and anti-freeze mixture
  • Radiator condition
  • Collapsed or restricted radiator hoses
  • Radiator pressure cap
  • Overflow system
  • Fan rotational direction
  • Fuses

Are all items normal?		 Yes Go to the next step.
No Service if necessary.
Repeat Step 1.
2 Connect M-MDS to DLC-2.
Turn ignition switch to ON position (Engine off).
Retrieve any DTCs.
Are there any DTCs displayed?		 Yes DTC is displayed: 
Go to appropriate DTC test.
No No DTC is displayed: 
Go to the next step.
3 Start engine and run it at idle speed.
Turn A/C switch on and set blower fan to any speed.
Does A/C compressor engage?		 Yes Go to Step 5.
No Inspect for the following and repair or replace if necessary:
  • Refrigerant charging amount
  • Open circuit between A/C relay and PCM terminal 1I
  • Seized A/C magnetic clutch
  • A/C magnetic clutch malfunction

If all items are okay, go to the next step.
4 Start the engine and run it at idle speed.
Access AC_REQ PID using M-MDS.
Turn A/C switch on and set blower fan any speed.
Does the PID turn ON and OFF properly?
(See PCM INSPECTION ).		 Yes Go to the next step.
No Inspect the following:
  • Refrigerant pressure switch operation
  • A/C switch is stuck open.
  • Open or short circuit between refrigerant pressure switch and PCM terminal 1AU
  • Open circuit of blower motor fan switch and resistor (if blower motor does not operate)
  • Evaporator temperature sensor and A/C amplifier
5 Inspect cooling fan control system operation.
(See COOLING FAN CONTROL SYSTEM INSPECTION ).
Does cooling fan control system work properly?		 Yes Go to the next step.
No Repair or replace malfunctioning parts.
6 Is drive belt normal? Yes Go to the next step.
No Replace drive belt.
7 Is there any leakage around heater unit in passenger compartment? Yes Inspect and service heater for leakage.
No Go to the next step.
8 Is there any leakage at coolant hoses and/or radiator? Yes Replace malfunctioning part.
No Go to the next step.
9 Cool down the engine.
Remove thermostat and inspect operation.
(See THERMOSTAT REMOVAL/INSTALLATION ).
(See THERMOSTAT INSPECTION ).
Is thermostat normal?		 Yes Engine coolant temperature and thermostat are okay, inspect engine block for leakage or blockage.
No Access ECT PID.
Inspect for both ECT PID and temperature gauge readings.
If temperature gauge on instrument cluster indicates normal range but ECT PID is not same as temperature gauge reading, inspect ECT sensor.
If temperature gauge on instrument cluster indicates overheating but ECT PID is normal, inspect temperature gauge and heat gauge unit.
10 Verify test results.
  • If okay, return to diagnostic index to service any additional symptoms.
  • If malfunction remains, inspect related Service Bulletins and/or On-line Repair Information and perform repair or diagnosis.
    • If vehicle is repaired, troubleshooting completed.
    • If vehicle is not repaired or additional diagnostic information is not available, reprogram PCM if later calibration is available. Retest.
scientia non olet · About LEMON Manuals