P0128 – Audi DTC

Audi DTC P0128 – Defective Engine Thermostat, Defective Engine Coolant Temperature Sensor, Defective Intake Air Temperature Sensor, Defective Cooling System, Low Engine Coolant, Dirty Engine Coolant causing incorrect Coolant Temperature Sensor readings, Defective/always running Engine Cooling fan(s)

DTC P0128 meaning on Audi

DTC P0128 indicates that the engine coolant temperature is not reaching the expected operating temperature within a specified time frame. This code is triggered when the Engine Control Module (ECM) detects that the coolant temperature is below the threshold, typically around 185°F (85°C), after a certain period of engine operation. This can lead to inefficient engine performance and increased emissions.

Audi DTC P0128 symptoms

Common symptoms associated with DTC P0128 may include:

• Check Engine Light illuminated
• Engine running cooler than normal
• Poor fuel economy
• Increased emissions
• Heater not functioning properly

Audi DTC P0128 causes

Several factors can lead to the triggering of DTC P0128, including:

• Defective Engine Thermostat
• Defective Engine Coolant Temperature Sensor
• Defective Intake Air Temperature Sensor
• Defective Cooling System
• Low Engine Coolant
• Dirty Engine Coolant causing incorrect Coolant Temperature Sensor readings
• Defective or always running Engine Cooling fan(s)

Audi DTC P0128 seriousness

DTC P0128 can be considered a moderate issue. While it may not cause immediate engine damage, it can lead to:

• Reduced engine efficiency
• Increased fuel consumption
• Potential long-term damage if left unaddressed
• Failure to pass emissions tests

How to diagnose DTC P0128 on Audi

To diagnose DTC P0128, follow these steps:

1. Use an OBD-II scanner to confirm the presence of DTC P0128.
2. Check the engine coolant level and condition.
3. Inspect the engine thermostat for proper operation.
4. Test the Engine Coolant Temperature Sensor for accurate readings.
5. Examine the Intake Air Temperature Sensor for faults.
6. Check the operation of the engine cooling fan(s).

How to fix DTC P0128 on Audi step-by-step instructions

To fix DTC P0128, follow these steps:

1. Inspect and replace the engine thermostat if it is stuck open.
2. Replace the Engine Coolant Temperature Sensor if it is faulty.
3. Check and replace the Intake Air Temperature Sensor if necessary.
4. Inspect the cooling system for leaks and repair as needed.
5. Ensure the engine coolant is at the proper level and is clean.
6. Replace dirty coolant and flush the cooling system if required.
7. Test the engine cooling fan(s) and replace if they are defective.

How to erase DTC P0128 on Audi

To erase DTC P0128, follow these steps:

1. Connect an OBD-II scanner to the vehicle’s diagnostic port.
2. Access the diagnostic menu and select the option to clear codes.
3. Confirm the action to erase the DTC.
4. Disconnect the scanner and start the engine to verify that the code does not return.