Error Code P0128

Error Code P0128 Explained

Have you ever seen Check Engine Light illuminate on your dashboard and then encountered the error code P0128 when scanning for diagnostic?

P0128 is a common OBD Diagnostic Trouble Code (DTC). In this blog we will explain the error code P0128, causes, symptoms and how to fix it.

 

What is Error Code P0128

Diagnostic Trouble Code P0128 indicates a problem with your vehicle’s coolant temperature. Specifically, it means your vehicle coolant temperature is below the optimum temperature (usually less than 170-degree Fahrenheit).

Engine needs to run at an optimal temperature for efficient combustion, fuel economy, and emissions control. If the engine control module detects that the coolant temperature is below the expected temperature, it triggers the P0128 error code

 

What causes the Eror Code P0128

1.     Faulty Thermostat

The most common cause of P0128 is a malfunctioning thermostat. The thermostat controls the flow of coolant to regulate the engine temperature. If the thermostat gets stuck open or fails to close properly, the engine might struggle to reach its optimal temperature.

 

2.     Low Coolant Level

If your car is low on coolant, the engine may not have enough coolant to reach the proper operating temperature. Coolant leaks from the radiator or hoses can cause this issue.

 

3.     Faulty Coolant Temperature Sensor

The coolant temperature sensor monitors the engine’s coolant temperature and sends the data to the ECM. If the sensor is faulty or sending incorrect data, it could trigger the P0128 error code.

 

4.     Worn or Broken Wiring or Connectors

Damaged or corroded wiring and connectors can cause issues with the coolant temperature sensor and the thermostat, leading to inaccurate readings and a P0128 code.

 

5.     Fault in Engine Control Module

Very rarely P0128 error code shows up due to engine control module malfunction. This is very rare but if all other components work properly then this could be the problem.

 

What are the symptoms of Error Code P0128

Check Engine Light -The most obvious symptom of a P0128 code is the Check Engine Light. When the coolant temperature is out of range, the ECM will trigger the CEL to alert you of the problem.

Poor Engine Performance- Since the engine is not warming up properly, it might run less efficiently, leading to poor performance. You may notice reduced power, sluggish acceleration, or rough idle.

Reduced fuel Efficiency - Since the engine is not warming up properly, it might run less efficiently, leading to poor performance. You may notice reduced power, sluggish acceleration, or rough idle.

Heater Not Working - If the engine is not reaching the proper operating temperature, the vehicle’s heater may not work effectively.

Overheating - if the thermostat is stuck closed, it could lead to an overheating engine. This is more likely to happen in severe cases and could cause additional damage to the engine.

 

How to Fix Error Code P0128

To fix P0128, you must find the underlying cause. Here are few potential solutions:

Replace the thermostat

Top Off or Replace Coolant

Check and replace coolant temperature sensor

Inspect the wiring and connectors

Fic the issue in Engine Control Module

It is always advisable to seek for professionals’ support if you couldn’t find the reason for the fault code.

 

Frequently Asked Questions on P0128

 

1.     How serious is the P0128 error code?

The P0128 error code isn’t typically a major issue, but it can affect engine performance, reduce fuel efficiency, and potentially cause the engine to overheat. It’s important to address this problem sooner rather than later to prevent further damage.

 

2.     Can I drive with a P0128 code?

Yes you can drive with the P0128 code for a short period, but it's best to have the issue resolved quickly to avoid engine damage and to maintain optimal fuel efficiency.

 

3.     How much does it cost to fix the P0128 error code?

The cost to repair the P0128 code varies depending on the issue. Replacing the thermostat usually ranges from £100 to £300, while fixing the coolant temperature sensor or performing a coolant flush can be less expensive. Always ask for an estimate from your mechanic before proceeding.

 

4.     Can low coolant cause the P0128 code?

Yes, low coolant can lead to the engine running cooler than normal, triggering the P0128 error. It’s important to check the coolant levels regularly and top up if needed.

 

5.     Can a faulty ECM cause the P0128 code?

Although it’s uncommon, a defective engine control module (ECM) can cause the P0128 error. If no other issues are found, the ECM may need to be inspected.