2010 Cadillac CTS Sedan AWD V6-3.6L Page 846
Exhaust/Engine/Actuators and Solenoids - Engine/Variable Valve Timing Solenoid/Service and Repair/Camshaft Position Actuator Solenoid
Valve Solenoid Replacement - Bank 2 (Left Side) Intake)
* Camshaft Position Actuator Solenoid Valve Solenoid Replacement - Bank 2 (Left Side) Exhaust (See: Engine, Cooling and
Exhaust/Engine/Actuators and Solenoids - Engine/Variable Valve Timing Solenoid/Service and Repair/Camshaft Position Actuator Solenoid
Valve Solenoid Replacement - Bank 2 (Left Side) Exhaust)
* Camshaft Position Actuator Replacement - Bank 1 (Right Side) Intake (See: Engine, Cooling and Exhaust/Engine/Camshaft, Lifters and
Push Rods/Camshaft/Service and Repair/Camshaft Position Actuator Replacement - Bank 1 (Right Side) Intake)
* Camshaft Position Actuator Replacement - Bank 1 (Right Side) Exhaust (See: Engine, Cooling and Exhaust/Engine/Camshaft, Lifters and
Push Rods/Camshaft/Service and Repair/Camshaft Position Actuator Replacement - Bank 1 (Right Side) Exhaust)
* Camshaft Position Actuator Replacement - Bank 2 (Left Side) Intake (See: Engine, Cooling and Exhaust/Engine/Camshaft, Lifters and Push
Rods/Camshaft/Service and Repair/Camshaft Position Actuator Replacement - Bank 2 (Left Side) Intake)
* Camshaft Position Actuator Replacement - Bank 2 (Left Side) Exhaust (See: Engine, Cooling and Exhaust/Engine/Camshaft, Lifters and
Push Rods/Camshaft/Service and Repair/Camshaft Position Actuator Replacement - Bank 2 (Left Side) Exhaust)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup, and programming
P012B
DTC P0128 (w/LLT)
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic Procedure
Instructions)provides an overview of each diagnostic category.
DTC Descriptors
DTC P0128
- Engine Coolant Temperature (ECT) Below Thermostat Regulating Temperature
Circuit Description
The engine control module (ECM) monitors the temperature of the engine coolant for engine control and as an enabling criteria for some
diagnostics. The amount of air flow into an engine is proportional to the amount of heat an engine generates. The ECM monitors the amount of air
flow into the engine to calculate engine coolant temperature (ECT). The ECM uses the calculated temperature to determine if the engine has
warmed up to the closed loop temperature or to the thermostat regulating temperature. If the coolant temperature does not increase normally or does
not reach the closed loop temperature, diagnostics that use the ECT as enabling criteria, may not run when expected.
Conditions for Running the DTC
P0128
* Before the ECM can report DTC P0128 failed, DTC P0117 and P0118 must run and pass.
* DTCs P0100, P0101, P0102, P0103, P0111, P0112, P0113, P0116, P0117, P0118, P0119, or P0700 is not set.
* The engine speed is greater than 760 RPM.
* The ECT is colder than 70掳C (158掳F) at start up.
* The vehicle speed is greater than 8 km/h (5 mph).
* The air flow coming into the engine has accumulated to greater than 1,000 grams.
* DTC P0128 runs continuously once the above conditions have been met for approximately 15 minutes.
OR
* DTCs P0116, P0117, P0118, or P0119 is not set.
* The engine speed is greater than 25 RPM.
* The block heater is not detected.
* DTC P0128 runs continuously once the above conditions have been met for approximately 8 minutes
Conditions for Setting the DTC
P0128
* The ECM detects that the actual engine coolant temperature is 11掳C (20掳F) colder than the calculated thermostat regulating temperature of 89
掳C (192掳F), for greater than 4 seconds or for a cumulative of 30 seconds.
OR
* The ECM detects that the actual engine coolant temperature is 10掳C (18掳F) colder than the calculated ECT for greater than 1 second or a
cumulative of 10 seconds.
Action Taken When the DTC Sets
DTC P0128 is a Type B DTCs.
