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Chrysler PT Cruiser. Manual - part 245

Symptom:

P0125-CLOSED LOOP TEMP NOT REACHED

When Monitored and Set Condition:

P0125-CLOSED LOOP TEMP NOT REACHED

When Monitored:

With the engine running for at least 15 minutes, idling and no Engine

Coolant Temperature Sensor or MAF Sensor DTCs.

Set Condition:

The engine temperature does not go above 18°C (64°F). Two trips are

required to set this DTC.

POSSIBLE CAUSES

LOW COOLANT LEVEL

THERMOSTAT OPERATION

ENGINE COOLANT TEMPERATURE SENSOR

TEST

ACTION

APPLICABILITY

NOTE: If a ECT DTC set along with this code, diagnose the ECT DTC first.
NOTE: Inspect the ECT terminals and related PCM terminals. Ensure the
terminals are free from corrosion and damage.
NOTE: The best way to diagnose this DTC is to allow the vehicle to sit
overnight outside in order to have a completely cold soaked engine.
Note: Extremely cold outside ambient temperatures may have caused this
DTC to set.
WARNING: Never open the cooling system when the engine is hot. The
system is under pressure. Extreme burns or scalding may result. Allow the
engine to cool before opening the cooling system.
Check the coolant system to make sure that the coolant has the proper mixture, is in
good condition, and at the proper level.
Is the coolant level and condition OK?

All

Yes

→ Go To 2

→ Inspect the vehicle for a coolant leak, a pressure test may be

necessary. Repair the leak and add the necessary amount of
coolant.
Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

DRIVEABILITY - 1.6L GAS

TEST

ACTION

APPLICABILITY

Note: This test works best if performed on a cold engine (cold soak)
Turn the ignition on.
With the DRBIII

t, read the Eng Coolant Temp Deg value. If the engine was allowed

to sit overnight (cold soak), the temperature value should be a sensible value that is
somewhere close to the ambient temperature.
Note: If engine coolant temperature is above 82°C (180°F), allow the engine
to cool until 65°C (150°F) is reached.
Start the Engine.
During engine warm-up monitor the Eng Coolant Temp Deg value. The temperature
value change should be a smooth transition from start up to normal operating temp
82°C (180°F) . Also monitor the actual coolant temperature with a thermometer.
NOTE: As the engine warms up to operating temperature, the actual coolant
temperature (thermometer reading) and the Eng Coolant Tmp Deg in the
DRBIII

t values should stay relatively close to each other.

Using the appropriate service information, determine the proper opening tempera-
ture of the thermostat.
Did the thermostat open at the proper temperature?

All

Yes

→ Go To 3

→ Replace the thermostat.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

Turn the ignition on.
With the DRBIII

t, read the Eng Coolant Temp Deg value. If the engine was allowed

t remain

relatively the same with a

All

Yes

→ Test Complete.

→ Replace the Engine Coolant Temperature Sensor.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

DRIVEABILITY - 1.6L GAS

P0125-CLOSED LOOP TEMP NOT REACHED —

Continued

Symptom:

P0128-COOLANT THERMOSTAT

When Monitored and Set Condition:

P0128-COOLANT THERMOSTAT

When Monitored:

Key on, engine running. ECT at start between -6 C and 45 C. Idle % <

50% and Decel % < 50%.

Set Condition:

ECT remains below calculated coolant temp for more than 6 seconds.

POSSIBLE CAUSES

COOLANT LEVEL

COOLANT TEMPERATURE

INTERMITTENT CONDITION

TEST

ACTION

APPLICABILITY

WARNING: Never open the cooling system when the engine is hot. The
system is under pressure. Extreme burns or scalding may result. Allow the
engine to cool before opening the cooling system.
Check coolant mixture and the cooling system level.
If coolant level is low, check for visible leaks or perform a pressure test on the coolant
system.
Was the coolant level low and where any leaks found.

All

Yes

→ Repair the coolant leak and/or fill coolant to the proper level.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

→ Go To 2

Start engine and let the vehicle warm up to operating temperature.
WARNING: When the engine is operating, do not stand in a direct line with
the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear
loose clothing.
With the DRBIII

t in Inputs/Outputs, monitor the Coolant Temperature Sensor

value.
Does the coolant temperature increase normally and display within 5 degrees of
Calculated Coolant Te

All

Yes

→ Go To 3

→ Replace thermostat and fill coolant level to proper level.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

DRIVEABILITY - 1.6L GAS

TEST

ACTION

APPLICABILITY

The conditions that set the DTC are not present at this time. The following list may
help in identifying the intermittent condition.
WARNING: When the engine is operating, do not stand in a direct line with
the fan. Do not put your hands near the pulleys, belts, or fan. Do not wear
loose clothing.
With the engine running at normal operating temperature, monitor the DRBIII

parameters related to the DTC while wiggling the wiring harness. Look for param-
eter values to change and/or a DTC to set.
Review the DRBIII

t Freeze Frame information. If possible, try to duplicate the

conditions under which the DTC was set.
Refer to any Technical Service Bulletins (TSB’s) that may apply.
Visually inspect the related wiring harness. Look for any chafed, pierced, pinched, or
partially broken wires.
Visually inspect the related wiring harness connectors. Look for broken, bent, pushed
out, or corroded terminals.
Were any of the above conditions present?

All

Yes

→ Repair as necessary.

Perform POWERTRAIN VERIFICATION TEST VER - 5 - 1.6L.

→ Test Complete.

DRIVEABILITY - 1.6L GAS

P0128-COOLANT THERMOSTAT —

Continued

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