Previous P0400 code returned and now have P030x codes and P01316

Hi all

So my XKR 4.0 (2002 UK model) previously had the P0400 code back in April:

I did a clean up with carb cleaner and the error code never came back… until last week (i.e. 6 months later). Typically, as I’m trying to sell her…!!

So, I did the same clean up. Error went but I felt the engine sounded ‘rougher’.

Today, engine warning light came back and I checked my codes… HORROR!

P0303, P0304, P0305, P0306, P0308

Eek. I’ve done some googling and get what these are all about in general… I guess it’s unlikely to be the spark plugs as there’s 5 different ones showing; wasn’t sure if there were individual coils for each cylinder (some of the posts I read were for different model cars/engines) or a single coil pack? If single coils then again I guess it’s unlikely to be the coils… but is there one ‘pack’ that covers them all on this car? Similarly, I guess it’s unlikely for it to be spark cables as they also wouldn’t suddenly all go at once would they…?

Any advice greatly appreciated!!

Also… should I be driving the car at all??


Individual coil packs on these engines, when was the last time you changed the plugs?
If the codes say mis fire then start with the plugs but expect to change out the coils as well.

Hi Robin. The service history isn’t great, not sure when they were last done so perhaps that’s worth trying.

Thing is, I started her up this morning and she sounded fine, so thought I’d clear the codes and see if the engine warning light came back on - it didn’t. Drove her for a few mins, no light appeared. Turned off and back on, nothing. Took her out for a longer 20 min drive at lunch and still no light & no codes. So could it be a mis-read? Car sounds fine. Idles smoothly and quietly, pulls nicely. Only thing of note is that I think she’s making more of a ‘fluttery’ noise when accelerating hard; I’m not very observant / don’t have a “good ear” for car sounds though so she may have always been doing that!!

Some times the ECU will get a bit confused if the car is started and then shut off early before it is warm, not every time but it can happen. This may be one of those times?
Continue to drive it and and see if the fault re-occurs.

Thanks Robin, let’s hope it’s just the ECU getting confused :slight_smile: