Fault Conditions

Engine Coolant Temperature Circuit. Performance Problem.







Fault symptoms
- CHECK ENGINE.
- 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 condition for this diagnostic trouble code: Atmospheric pressure must exceed 72 kPa as well as coolant and intake c temperature 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 g/s. A maximum is set for the substitute value after 350 s that is dependent on the intake air temperature (normally 65-80C). 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.

Dependents:
- P0112 and P0113.

System reaction to a fault:
- A substitute value is continually calculated according to the following method: Intake air temperature at start is incremented 1 ° per 60 g air mass/sec. The value is maximized to 90 °C and is used as soon as the fault criteria for the sensor is fulfilled.

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

Fault handling: Fault Handling III, Other Emission-Related Component & Function
- 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 value, unit C.

For information, Tech 2 Menu Structure, DTC Menu, Read Value, Activate, Sys Info

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.

Proceed to Diagnostic Procedures Checking Coolant