The Tyre Pressure Monitoring System (TPMS) is a crucial safety feature in modern vehicles, designed to alert drivers when tyre pressure falls below a safe level. However, if the TPMS warning lamp illuminates during an MOT test, it can indicate a malfunctioning or faulty system, potentially leading to an MOT failure. This comprehensive guide delves into the technical specifications, causes, and solutions for TPMS-related MOT failures, empowering you to avoid these issues and ensure a smooth MOT experience.
Understanding TPMS Sensor MOT Failure
The TPMS is a mandatory feature in all new vehicles registered after 2012 in the UK. It continuously monitors the air pressure in each tyre and alerts the driver when the pressure falls below a predetermined threshold. During an MOT test, the TPMS system is evaluated to ensure it is functioning correctly.
If the TPMS warning light illuminates during the MOT, it indicates a system malfunction, rather than just low tyre pressure. This is considered a major defect, and the vehicle will fail the MOT test. The MOT guidelines state that a malfunctioning TPMS system is a major fault, leading to an automatic MOT failure.
Common Causes of TPMS Sensor MOT Failure
-
Battery Failure: TPMS sensors are equipped with internal batteries that have a limited lifespan, typically lasting 5-7 years or 100,000 miles. As the battery depletes, the sensor may fail to transmit the correct tyre pressure data, triggering the warning light.
-
Battery Life Expectancy: TPMS sensors are powered by lithium-ion or lithium-metal batteries, which have an average lifespan of 5-7 years or 100,000 miles of use.
-
Battery Replacement: When the TPMS sensor battery fails, the entire sensor unit must be replaced, as the batteries are not designed to be user-replaceable.
-
Valve Stem Problems: The valve stem is an integral part of the TPMS sensor, responsible for transmitting tyre pressure data. Over time, the valve stem can corrode or become brittle due to exposure to road conditions, leading to sensor failure.
-
Valve Stem Lifespan: The valve stem typically has a lifespan of 5-7 years, depending on driving conditions and environmental factors.
-
Valve Stem Replacement: When the valve stem becomes damaged, the entire TPMS sensor unit must be replaced, as the valve stem is not designed to be serviced separately.
-
Sensor Malfunction: TPMS sensors can also fail due to internal component issues, such as faulty electronics or mechanical problems. This can result in the sensor providing inaccurate tyre pressure readings or failing to communicate with the vehicle’s TPMS system.
-
Sensor Failure Rates: TPMS sensor failure rates can vary depending on the vehicle make, model, and driving conditions, but typically range from 5-10% over the lifetime of the vehicle.
-
Sensor Replacement: When a TPMS sensor fails, the entire sensor unit must be replaced to restore the system’s functionality.
-
Sensor Incompatibility: In some cases, the TPMS sensors may not be compatible with the vehicle’s make and model, leading to system malfunctions and MOT failure.
-
Sensor Compatibility: TPMS sensors are designed to be specific to the vehicle make, model, and year. Using the wrong sensors can result in system incompatibility and MOT failure.
- Sensor Replacement: When replacing TPMS sensors, it is crucial to use the correct sensors recommended by the vehicle manufacturer to ensure compatibility and proper system operation.
Avoiding TPMS-related MOT Failures
To avoid TPMS-related MOT failures, it is essential to maintain the TPMS system and ensure it is functioning correctly. Here are some key steps to take:
-
Regular Tyre Pressure Checks: Regularly check the tyre pressure in all four tyres and maintain the recommended pressure levels. This can help prevent the TPMS warning light from illuminating due to low tyre pressure.
-
Tyre Condition Inspection: Manually inspect the tyres for any signs of wear, damage, or punctures. This can help identify potential issues that may affect the TPMS sensors.
-
TPMS System Servicing: Periodically have the TPMS system serviced by a qualified technician. This can include checking the sensor batteries, valve stems, and overall system functionality.
-
Sensor Replacement: If a TPMS sensor is found to be faulty, replace it with the correct sensor recommended by the vehicle manufacturer. Ensure the new sensor is properly programmed and calibrated.
-
Sensor Compatibility: When replacing tyres or wheels, ensure the new TPMS sensors are compatible with the vehicle’s make, model, and year. Consult the vehicle’s owner’s manual or a qualified technician for guidance.
By following these steps, you can proactively maintain the TPMS system and avoid TPMS-related MOT failures, ensuring a smooth and successful MOT experience.
Conclusion
The Tyre Pressure Monitoring System (TPMS) is a critical safety feature in modern vehicles, and its proper functioning is essential for passing the MOT test. Understanding the common causes of TPMS sensor MOT failure, such as battery depletion, valve stem issues, and sensor malfunctions, can help you take the necessary steps to prevent these issues and ensure a successful MOT outcome.
By regularly checking tyre pressures, inspecting tyre conditions, and servicing the TPMS system, you can proactively maintain the system and avoid TPMS-related MOT failures. Remember, when replacing TPMS sensors, it is crucial to use the correct sensors recommended by the vehicle manufacturer to ensure compatibility and proper system operation.
With this comprehensive guide, you can confidently navigate the TPMS-related aspects of the MOT test and keep your vehicle in top condition, ensuring a smooth and hassle-free MOT experience.
References:
- Blackcircles.com – The legalities around TPMS
- Kwik Fit – How To Avoid An MOT Test Failure Due To Faulty TPMS
- Halfords UK – Is tyre pressure checked at an MOT?
- Ford Kuga Owners Club Forums – TPMS and MOT
- Car Clinic MOT Centre – Faulty TPMS Results In MOT Failure