If you are an owner of the Vauxhall Mokka popular compact SUV, you may have come across the Code 89 warning message on your dashboard. This error code can be caused by various issues related to the vehicle’s engine and fuel system.
Understanding the potential causes of this code and how to fix them can save you time and money in the long run. Now you may be thinking about what are the causes and solutions for code 89 on Vauxhall Mokka.
Possible causes of Code 89 include a faulty engine coolant temperature sensor, wiring issues, or ECU malfunction. To fix the code, first, check all related wiring and connectors for any damage or loose connections. If the wiring appears to be in good condition, then you should replace the engine coolant temperature sensor or ECU.
In this guide, we’ll dive deeper into the causes of Code 89, how to diagnose the problem, and the steps you can take to fix it.
What Does Warning Code 89 Mean On A Vauxhall Mokka?
Warning code 89 on a Vauxhall Mokka typically indicates a fault in the engine’s sensor circuit, specifically related to the catalytic converters. The code may also be triggered by a faulty thermostat or a problem with the engine’s exhaust system.

The check engine light may illuminate when this code appears. It is recommended to take the vehicle to a professional mechanic for diagnosis and repair. The cost of repair will depend on the specific issue and the level of damage.
So, address warning codes promptly to prevent further damage to the engine and to maintain the vehicle’s fuel economy and performance. Regular maintenance, such as oil changes and monitoring the coolant level, can also extend the life of the engine.
Possible Causes of Code 89 on Vauxhall Mokka
If you have seen the check engine light on your dashboard with code 89, it indicates that there is an issue with the engine. Here are some possible causes of this error code:
Engine Coolant Temperature Sensor Malfunction
The engine coolant temperature sensor is responsible for monitoring the temperature of the engine and sending that information to the engine control unit (ECU). A malfunctioning sensor may cause the ECU to think that the engine is overheating, triggering the code 89 warning.
Wiring Issues
If the wiring connections to the engine coolant temperature sensor are loose or damaged, it can also trigger code 89. This is because the ECU is unable to receive accurate temperature readings from the sensor due to the wiring issues.
ECU Malfunction
In some rare cases, a malfunctioning ECU can also be responsible for the code 89 warning. If the ECU is not receiving accurate temperature readings from the engine coolant temperature sensor, it may display this error code.
Low Coolant Level
A low coolant level can also trigger the code 89 warning. This is because the engine coolant helps to regulate the temperature of the engine, and a low level can cause the engine to overheat.
Failed Thermostat
A failed thermostat can also cause the engine to overheat and trigger the code 89 warning. The thermostat regulates the flow of coolant through the engine and if it fails, it can cause the engine to overheat.
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How to Diagnose Code 89 on Vauxhall Mokkar?
If you are experiencing a code 89 on your Vauxhall Mokka, it could indicate a problem with the engine’s cooling system. Here are some steps to diagnose and potentially fix the issue:
- Use an OBD2 Scanner: An OBD2 scanner can help you read and clear the trouble codes that your vehicle’s computer is generating. This will give you a better idea of what is causing code 89 to appear.
- Check the Coolant Level: If your coolant level is low, it could be causing the engine to overheat and generate a code 89. Check the coolant level and add more if necessary.
- Inspect Wiring and Connections: A loose or damaged wire or connection in the cooling system can also trigger a code 89. Inspect all connections and wiring to ensure they are secure and free from damage.
- Check Thermostat Function: A faulty thermostat can also cause issues with the cooling system and trigger a code 89. Check the thermostat to ensure it is functioning properly.
- Perform a Compression Test: A compression test can help you determine if there are any issues with the engine’s internal components, such as the head gasket or piston rings. If the compression test reveals any issues, further repairs may be necessary.
How to Fix Code 89 on Vauxhall Mokka?
Code 89 on a Vauxhall Mokka is an error code that indicates a problem with the engine coolant temperature sensor. It can also be caused by faulty wiring and connections, a malfunctioning ECU, low coolant level, or a bad thermostat. Here are some possible fixes for Code 89:

1. Replace the Engine Coolant Temperature Sensor
The engine coolant temperature sensor is responsible for monitoring the temperature of the coolant and sending signals to the engine control unit (ECU) to adjust fuel injection and ignition timing. If the sensor is faulty or damaged, it can trigger Code 89. A mechanic can replace the sensor to resolve the issue.
2. Repair or Replace Faulty Wiring and Connections
Sometimes Code 89 can be caused by faulty wiring or connections between the engine coolant temperature sensor and the ECU. A mechanic can inspect the wiring and connections to identify and fix any issues.
3. Replace the ECU
If the engine coolant temperature sensor and wiring are not the issue, it may be a problem with the ECU itself. In this case, a mechanic may need to replace the ECU to fix the problem.
4. Add Coolant to the System
Low coolant level can also trigger Code 89. Check the coolant level and add more if needed. If the coolant level is consistently low, there may be a leak in the system that needs to be repaired.
5. Replace the Thermostat
A bad thermostat can cause the engine to overheat, which can trigger Code 89. A mechanic can inspect and replace the thermostat if needed.
Preventing Tips for Code 89 on Vauxhall Mokka
Code 89 can be caused by several factors, such as a faulty sensor, a bad thermostat, or problems with the exhaust system. Here are some tips to prevent code 89 on your Vauxhall Mokka:
Regular Maintenance and Inspections
Regular maintenance and inspections are crucial to prevent code 89 and other engine-related problems. Follow the manufacturer’s recommended maintenance schedule, which includes regular oil changes, filter replacements, and coolant level checks. Additionally, have your Mokka inspected by a professional mechanic to detect any issues early on.
Using High-quality Coolant
Using high-quality coolant is essential to prevent code 89 on your Vauxhall Mokka. Use a coolant that meets the manufacturer’s specifications and replace it regularly. Low-quality coolant or old coolant can cause corrosion and damage to the engine, leading to code 89.
Properly Maintaining the Engine
Properly maintaining the engine is another essential factor in preventing code 89. Keep the engine oil at the proper level and replace it regularly. Additionally, inspect the exhaust system regularly for any leaks or damage that could cause code 89.
Not Ignoring Warning Signs
If you notice any warning signs, such as the check engine light or unusual engine noise, don’t ignore them. Ignoring warning signs can lead to more severe problems and more expensive repairs in the long run. Instead, have your Mokka inspected by a professional mechanic as soon as possible.
Wrapping Up
Code 89 on Vauxhall Mokka is a common issue that can be caused by various factors, such as a faulty fuel pump, an air filter problem, or an issue with the air mass meter. Fortunately, it is not difficult to identify and address the issue, as long as the necessary diagnostic tools are available.
With the help of a reliable mechanic or a DIY guide, the issue can be addressed, and the vehicle should be running smoothly again. Therefore, code 89 on a Vauxhall Mokka should not be seen as an insurmountable issue, as long as the right steps are taken to diagnose and fix it properly.