18 Cooling System Concerns-Runs Cold [Lf] - Mazda 3 Workshop Manual

Mazda 3 Workshop Manual – Engine + Wiring Diagrams + Diagnostic Trouble Codes
(See THERMOSTAT
REMOVAL/INSTALLATION
(See THERMOSTAT INSPECTION
[LF].)
Is thermostat normal?
Verify test results.
• If normal, return to diagnostic index to service any additional symptoms.
(See ENGINE SYMPTOM TROUBLESHOOTING
• If malfunction remains, inspect related Service information perform repair or diagnosis.
10
- If vehicle repaired, troubleshooting completed.
- If vehicle not repaired or additional diagnostic information not available, replace the
PCM.
(See PCM REMOVAL/INSTALLATION
NO.18 COOLING SYSTEM CONCERNS-RUNS COLD
18
Engine takes excessive period for reaching normal operating temperature.
DESCRIPTION
• Thermostat malfunction
POSSIBLE CAUSE
• Cooling fan system malfunction
Diagnostic procedure
STEP INSPECTION
Is customer complaint "Lack of
1
passenger compartment heat" only?
Does the engine speed continue at
2
fast idle?
Downloaded from
[LF].)
No
[LF]
COOLING SYSTEM CONCERNS -RUNS COLD
RESULTS
Yes
No
Yes
https://carmanualshub.com/
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.
[LF].)
[LF].)
ACTION
Inspect A/C and heater system.
Go to the next step.
Go to symptom troubleshooting "No.9 Fast
idle/runs on".
(See NO.9 FAST IDLE/RUNS ON
- automotive repair manuals website
B3E010318881W20
[LF].)