Thermostat Monitor

OBD System Description - Thermostat Monitor

Thermostat Temp

DTC Description / Detecting Condition / Confirmation Procedure
P0128 refer to DTC P0128: ECT Below Thermostat Regulating Temperature. P0128

Monitor Strategy Description
The Thermostat Diagnostic monitors the time it takes for the coolant temperature to reach either the maximum temperature required to enable other diagnostics or the manufacturer recommended Thermostat Regulating Temperature -11 degrees C, and compares it against a threshold in order to make a PASS/FAIL determination, provided airflow and idle conditions are met.

Malfunction Criteria




Coolant Temperature < See table.

when




Timer > See table.

Enable Conditions
Test not complete = FALSE
AND Reporting allowed = FALSE
AND Disabling Faults Present = FALSE
AND Coolant sensor within range = TRUE
AND Minimum IAT >= -7 degrees C
AND Engine running = RUN
AND Startup coolant temp saved = TRUE
AND Thermostat target temp - Startup coolant temp >= 11 degrees C
Test will not report a failure if:




Accumulate Idle Time > See table.

AND




Accumulated Airflow < See table.

Time required
Time Length and Frequency:
Monitor runs once per key cycle.

Cool High Temp

DTC Description / Detecting Condition / Confirmation Procedure
P0217 refer to DTC P0217: Engine Coolant Over Temperature. P0217

Monitor Strategy Description
This diagnostic introduces a calibratable delay and simultaneously looks out for excessive engine loads. Once the delay period passes and excessive loads have not been experienced, the diagnostic checks whether the undefaulted coolant temperature has exceeded a maximum threshold in order to make a PASS/FAIL determination.

Malfunction Criteria
Coolant Temperature >= 107 degrees C

Enable Conditions
Engine running = RUN
AND Reporting allowed = FALSE
AND Disabling Faults Present = FALSE
AND Coolant sensor out of range = FALSE
AND Undefaulted Coolant Temp >= 50 degrees C
AND Undefaulted IAT >= 35 degrees C
AND (Soak time >= 360 min.
OR Undefaulted Coolant Temp <= 45 degrees C
AND Delay Timer > 60 sec.
AND Airflow conditions too high = FALSE
Test will not report a failure if:
EWMA Airflow > 33 g/sec.
AND Average Airflow > 35 g/sec.
OVER Airflow Evaluation time = 240 sec.

Time required
Time Length and Frequency:
Monitor runs once per key cycle