Diesel Engine coil light flashes

Pew_Pew_Pew_Lasers!

One or more glow plugs has failed, or you have a fault in the glow plug relay.

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vaio wrote: »

My van did the same this morning at about -6, turned ignition on, glow plug light on, took longer than normal to go out but when it did it started first touch as normal.

After about 200yards the light came back on and stayed on for maybe a couple of miles. I presume it’s temperature related in that even though it was running the block etc was so cold that it was below the switch on point for the glow plugs

Low temperatures are irrelevant to glow plugs. They're heaters, designed to aid starting. Most modern diesels have such high levels of compression they don't require glow plugs in anything but the coldest of conditions. That's what's most likely happened here, the glow plugs have been used, they remain on for the first minute or so (perfectly normal), and then one fails.

goldspanners

some engines will keep the glow plugs on for a few seconds after starting to help burn off the extra diesel being used to start the engine, but the light should not be on after the engine has started.

Pew_Pew_Pew_Lasers!

Correct. The light staying on is sometimes a visible indicator of a fault. Its usually very easy to diagnose, and a competent DIYer can replace them himself.

Exemplar

On checking my Fiat Punto diesel manual last night if the the glow plug light flashes after starting its telling you its cold outside!! Thats all, no issues.

BikerEd

daveyjp wrote: »

My X type did the same a couple of weeks ago. Started on three cylinders, spluttered then stopped, glow plug light flashing.

Flashing coil light on x-type can also be a general engine warning, most typically for the EGR valve, which may need replacing. Probably worth getting the thing hooked up on a diagnostic unit for confirmation of the exact problem.

EDIT: also worth noting that when the warning light comes on the engine goes into a low-power "limp home" mode which makes it feel exactly like it is running on three cylinders. Perhaps you do have a faulty plug, but it might be something else - hence the advice from me and the next post to get it diagnosed. Be aware that cheaper scanners like the Snap On Solus will not do all the Jaguar fault codes.

Lavendyr

I have a Seat Ibiza diesel. When the coil light flashes, on my car it means that the engine management system has reported a fault - which could mean any number of things. In my case when this happened recently, it was simply that a brake light switch had failed. The only way to know for sure what causes the fault is to take the car to a garage with diagnostics and plug it in.