Glow plug replacement

Q I bought my Vauxhall Insignia 2.0 diesel new in 2011 from a main dealer, and have always let them attend to all the servicing.

Last October, I got the ‘Service vehicle soon’ message and the dealer charged me £89 for a diagnostics check. The fault codes indicated that the glow plugs needed replacing, for which they wanted £577. Assuming these glow plugs perform the same task as on other diesels I have owned, I declined their offer and decided to do the job myself. I bought the Haynes manual to assist me, but how do you detach the lead to the glow plugs?

Also, I recently had the misfortune to catch the front lower bumper, and although relatively little damage was done, I needed a new bumper. I removed the original as per the Haynes manual, but fitting the new bumper is a bit trickier. Any ideas?

Tony Batchelor

A The lead to the glow plug is a push fit, but it can be very tight and care must be taken when removing it. The plugs cost around £80 each. It is also worth noting that some 2.0 Insignia engines have a pressure sensor built into the glow plug. As the 2011 Insignia could have been fitted with eight different 2.0 diesel engines, it is not possible to say which glow plugs your vehicle uses.

Removing the pencil-type glow plugs is a tricky job and there is always the possibility that the plug will either shear at the base or the probe will shear inside the engine. To minimise the risk, ensure that the engine has been warmed up before starting the job. It is not strictly necessary to remove the glow plugs to test them as this can be done using an ohmmeter. By removing the electrical plug and testing the resistance between terminal and earth, it should be possible to assess the condition of the glow plug. An open circuit will reveal a failed plug, as will a high resistance. The readings should fall somewhere between 0.3-0.9 ohms, but an odd reading will quickly reveal a faulty glow plug.

With regard to fitting the bumper, the best tip I can suggest is that the bumper needs to be offered up evenly across the width of the vehicle. This means that either a two-person approach is required or that one side of the bumper needs to be supported at the correct height while the other side is fitted in place.