Engine Coolant Temperature Circuit. Performance Problem.

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Fault symptoms

• A/C malfunctioning.
• Radiator fan running continuously when ignition is ON.
• Temperature gauge displaying incorrect value.
• Misfiring can occur before trouble code is generated.

On-Board Diagnostics

Type of diagnosis:

- Test 1 and 2: Once per driving cycle. Interrupted when fault criteria fulfilled or OK reported. Restarts next driving cycle.

Enable criteria:

- General conditions for this trouble code: Atmospheric pressure must exceed 72 kPa and the engine coolant and intake air temperatures must exceed -7°C.

- Test 1: Engine running. A counter accumulates the time during which the mass air flow has exceeded 10 g/s. Counter has reached 400 s.

- Test 2: Engine running. A substitute value is calculated for the engine coolant temperature: The starting intake air temperature is incremented with 1°C per 60 g air mass/s. A counter accumulates the time during which the air mass flow has exceeded 10 mg/s. An maximum is set for the substitute value after 350 s that is dependent on the intake air temperature (normally 65-80°C). The maximum value is set as soon as the air mass/combustion is not too high and the air mass/s is not too low, so that the intake air temperature will be as close as possible to the outdoor temperature. After 400 s, the sensor value will be compared with the substitute value.

Fault criteria:

- Test 1: Sensor value has changed less than 1°C.
- Test 2: Sensor value more than 20°C below substitute value or more than 48°C above substitute value.


- P0112 and P0113.

System reaction to a fault:

- A substitute value is calculated continuously as follows: Starting intake air temperature is incremented with 1°C per 60 g air mass/s. The value is maximized to 90°C and is used as soon as fault criteria for the sensor are fulfilled.

OK report:

- Test 1 and Test 2 performed once and fault criteria not fulfilled. Fault criteria for Test 1 not fulfilled. Fault criteria for P0117 or P0118 not fulfilled.

Fault handling: (See “Fault diagnosis, general” for more information.)

- Type III.

Diagnostic help

Fault diagnosis concerns an electrical fault in connecting leads or in the sensor. Functions in the diagnostic tool related to the fault:

• Diagnostic status for the diagnosis.
• Temperature sensor reading, in °C.

See also the description of readings under Menu "Read Values" for more information.

Checking the wiring

Jiggle the wiring harness at several points and in different directions to detect intermittent breaks and short circuits. Observe the multimeter, diagnostic tool or test lamp during the check.