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Home >> Mazda >> 2021 >> CX-9 Signature >> Repair and Diagnosis >> Engine Performance >> System >> Symptom Troubleshooting - Engine >> No. 9 Fast Idle/Runs On >> Notes
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No. 9 Fast Idle/Runs On: Notes

NO. 9 FAST IDLE/RUNS ON (SKYACTIV-G 2.5T) DESCRIPTION AND POSSIBLE CAUSE

9 FAST IDLE/RUNS ON
DESCRIPTION
  • Engine speed continues at fast idle after warm-up.
  • Engine runs after ignition is switched off.
POSSIBLE CAUSE
  • Cooling system malfunction
  • PCM DTC is stored
  • Accelerator pedal stuck depressed
  • Erratic signal to PCM
    • APP sensor or related circuit malfunction
    • Communication error between TCM and PCM
    • ECT sensor No. 1 or related circuit malfunction
    • A/F sensor or related circuit malfunction
    • HO2S or related circuit malfunction
      • Improper air/fuel mixture ratio control operation
  • Improper load signal input
    • Improper A/C request signal
  • Improper operation of drive-by-wire control system
  • Throttle body malfunction
  • Fuel injector malfunction
  • Spill valve control solenoid valve (built-into high pressure fuel pump) malfunction
  • Improper operation of cruise control system
  • Air leakage from intake-air system
  • Injector driver (built-into PCM) malfunction
    WARNING:
    • The following troubleshooting flow chart contains the fuel system diagnosis and repair procedures. Read the following warnings before performing the fuel system services:
      • Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage.

        Always keep sparks and flames away from fuel.

      • Highly pressurized fuel may spray out if the fuel line is cut. Due to the following dangers occurring with a fuel spray, always complete the "Fuel Line Safety Procedure" to prevent the fuel from spraying. (See BEFORE SERVICE PRECAUTION [SKYACTIV-G 2.5T] .)
  • Fuel may cause irritation if it comes in contact with skin and eyes.
    • If fuel ignites and causes a fire, it may lead to serious injury or death, and damage to property and facilities.
    CAUTION:
    • Disconnecting/connecting the quick release connector without cleaning it may possibly cause damage to the fuel pipe and quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.