Thermostat Monitor

OBD System Description - Thermostat Monitor

Thermostat_Temp

DTC Description / Detecting Condition / Confirmation Procedure
P0128 refer to [DTC P0128: Engine Coolant Temperature (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 °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 below.
when
Timer > = See table below.








Enable Conditions
Test not complete = FALSE
AND No Disabling Faults Present (Refer to Disabling Faults List - Included with certification documentation) = FALSE
AND Coolant sensor within range (Signal Value within ECT Low/High OOR) = TRUE
AND Minimum IAT greater than limit >= -7 °C
AND Engine running = RUN (3)
AND Startup coolant temp saved = TRUE
AND Thermostat target temp - Startup coolant temperature greater than threshold >= 11 °C
Test will not report a failure if:
Accumulate Idle Time longer than limit > See table below.
AND
Accumulated Airflow lower than limit < See table below.








Time required
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
The undefaulted coolant temperature must exceed a maximum threshold temperature in order for the diagnostic to FAIL >= 107 °C

Enable Conditions
Engine running = RUN
AND No disabling faults present (Refer to Disabling Faults List - Included with certification documentation) = FALSE
AND Coolant sensor within range (Signal Value within ECT Low/High OOR) = FALSE
AND Undefaulted Coolant Temp >= Min Threshold >= 50 °C
AND Undefaulted IAT >= Max Threshold >= 35 °C
AND (Long enough soak time >= 360 minutes
OR Undefaulted Coolant Temp >= Min Threshold <= 45 °C
AND Not excessive filtered airflow <= 33 g/s
AND Not excessive average airflow <= 35 g/s

Time required
Detection Time
1.25 seconds failure out of 2.38 seconds sample period Continuous Monitoring every 125.00 ms.
Detection Samples
10 test failures within 10 test samples at 125. ms loop time.