Faulty DPF sensor

The consumer’s issue:

“I took my car to the dealership to change the cambelt, and shortly after, my DPF light came on. The business told to me to replace the DPF at a cost of £2,400 because it was unable to read the level of soot content.

I then went to an independent garage for a second opinion, and they recommended that I replaced the DPF sensor. However, when they went to exchange it, they found that the existing sensor was not fully connected, thereby resulting in a false temperature reading, as well as excessive blockages and wear. The business therefore reconnected the sensor and the fault with the warning light was rectified.

Based on the above, I believe that the dealership forgot to reconnect the sensor when changing the timing belt, so I want them to pay for a replacement DPF, and for it to be installed by a third party garage that I can trust. In addition, the dealership should cover the cost of the replacement sensor that I paid for, but didn’t use. However, my claim was declined as the business believes that the sensor was reconnected in the correct way.”

The accredited business’ response:

  • The car was with us for a cambelt change and MOT.
  • We replaced the cambelt and refitted all the necessary parts. This was followed by an MOT test, which the car failed due to its shock absorbers.
  • From DVLA records, the car was MOT’d two days later by another garage, where the car passed its MOT. However, the customer made no record of this in their complaint.
  • As part of the MOT, the inspector will check the exhaust system and inspect the engine bay.
  • If there was a hole in the exhaust system, because of the failure to reconnect the sensors, then we would have noticed this during our MOT, plus the other garage which conducted the MOT two days later would have also seen a hole in the exhaust system had the sensor not been fitted correctly.
  • When the customer informed us about the DPF warning light, they said that the car needed a forced regeneration. We attempted the regeneration process, but the attempt failed. As a result, we recommended a replacement DPF in accordance with the manufacturer’s guided fault finding process and the fault codes shown by the car.
  • The customer later contacted us to state that a third party garage had found the sensor to be disconnected, leaving a hole in the exhaust system.
  • We disagree with the customer’s position that we left the sensor disconnected, so we won’t be covering the losses or providing a replacement DPF at our cost.

The adjudication outcome:

  • The adjudicator did not find that the business had failed to fit the sensor correctly or failed to follow the right diagnostic process.
  • This is because the failure to identify a hole in the exhaust system in the two MOTs conducted shortly after the dealership replaced the cambelt, indicates that the business reconnected the sensor correctly.
  • Furthermore, the business followed the manufacturer’s fault finding process, so they had not neglected the use of reasonable skill and care during the diagnostic process.


  • The customer and accredited business accepted the outcome as recommended by The Motor Ombudsman adjudicator and the case was closed.