DTC P0128 Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
HINT: This DTC relates to the thermostat.
DESCRIPTION This DTC is set when the Engine Coolant Temperature (ECT) does not reach 75C (167F) despite sufficient engine warm-up time
DTC No. |
DTC Detection Condition |
Trouble Area |
P0128 |
Conditions (a), (b) and (c) are met for 5 seconds (2 trip
detection logic):
|
|
MONITOR DESCRIPTION
The ECM estimates the ECT based on the starting temperature, engine loads, and engine speeds. The ECM then compares the estimated temperature with the actual ECT. When the estimated ECT reaches 75C (167F), the ECM checks the actual ECT. If the actual ECT is less than 75C (167F), the ECM interprets this as a malfunction in the thermostat or the engine cooling system and sets the DTC.
MONITOR STRATEGY
TYPICAL ENABLING CONDITIONS
TYPICAL MALFUNCTION THRESHOLDS
INSPECTION PROCEDURE
HINT: Read freeze frame data using the intelligent tester. The ECM records vehicle and driving condition information as freeze frame data the moment a DTC is stored. When troubleshooting, freeze frame data can be helpful in determining whether the vehicle was running or stopped, whether the engine was warmed up or not, whether the air-fuel ratio was lean or rich, as well as other data recorded at the time of a malfunction
1 CHECK ANY OTHER DTCS OUTPUT (IN ADDITION TO DTC P0128)
Result
HINT: If any DTCs other than P0128 are output, troubleshoot those DTCs first.
2 CHECK COOLING SYSTEM
3 INSPECT THERMOSTAT
Standard: 80 to 84C (176 to 183F)
HINT: In addition to the above check, confirm that the valve is completely closed when the temperature is below the standard.
REPLACE ECM
On-vehicle inspection
1. INSPECT STEERING PAD (VEHICLE NOT INVOLVED IN COLLISION)
Perform a diagnostic system check.
With the steering pad installed on the vehicle,
perform a visual check. If there are any defects as
mentioned below, replace the steering pad with a
new one:
Cuts, minute cracks or ...
Hood
COMPONENTS
Adjustment
HINT:
Since a centering bolt is used as a hood hinge mounting bolt
and hood lock mounting bolt, the hood and hood lock can not
be adjusted with them on. Substitute a bolt with a washer for
the centering bolt.
1. INSPECT HOOD SUB-ASSEMBLY
Check that the clearance is ...
How to proceed with
troubleshooting
The intelligent tester can be used in steps 4, 6, 8 and 9.
1 VEHICLE BROUGHT TO WORKSHOP
2 CUSTOMER PROBLEM ANALYSIS
3 PASSENGER AIRBAG ON/OFF INDICATOR CHECK
4 DTCs CHECK (Present and Past DTCs)
Check for DTCs.
Result
5 DTCs CHART
6 CIRCUIT INSPECTION
7 REPAIR
8 CLEAR DTCs (Present ...