Engine Management Light

[Elm Park Royal]

I have a 2003 XJ V8 4.2 Supercharged, and it is a splendid car in marvellous condition for its age and 135k mileage. However, it has a recent history of apparently erroneous EML display. Usually, and very inconveniently, I stop using it until I can get it into to my trusted specialist garage (which is not local and has about a 10-day horizon) to take it in. There, the system is cleared and reset but the fault can never be replicated and I'm sent away with a "customer to monitor" instruction. On the last occasion, it was cleared and I decided to carry on using the vehicle come what may. This time, the EML light remained off for a week then came back on for four days before disappearing again. That lasted for another week and now it has just come back on again. Performance remains excellent with no identifiable problems whatsoever. The diagnostics always report a MAP sensor defect. My trusted garage insists that there is no MAP fault, no wiring problem and no air leak.
Two questions: a) if I drive it with the EML light on whilst it performs perfectly normally will it ever "time out" with the EML light turning red forcing the car in to limp mode ? and b) I believe EML warnings can be self cleared. If so, what tool do I need and how does it work. Is it as simple as plugging it in and just pressing a few buttons?
I'd quite like a permanent solution without something more material occurring to force the issue.
Anyway, all advice and answers to a ) and b) much appreciated.
Many thanks

[Thixendale]

Hi,
I would strongly recommend getting your own OBDII reader.
I have one for my car (X350 4.2) and wouldn't be without it.
You plug it in ( which is possibly the most difficult part) and it will allow you to explore the systems and read error codes. This will allow you to investigate further yourself and there are many helpful people on these forums who may be able to interpret the codes you see.

I have an iCarsoft OBDII reader which I got for under £100.

In addition to reading the codes it does allow you to reset which is good for monitoring. You can also use it for live data whilst driving.

Tony

[andypryce]

Even a cheaper one will give you some codes and allow you to clear them.

[ptjs1]

Elm Park Royal.

As Andy has mentioned, even a £5 OBDII plug-in will enable you to read codes, real-time information and clear codes using a phone app. I use mine every week on someone's car. It's a cheap and easy investment before you may decide to purchase more expensive equipment.

As regards MAP codes on Jaguar engines (is it a P1108 you're getting?), they are pretty common as are MAF code errors. My X350 used to throw a MAF code on the same motorway rise each week and I never could work out why, even after cleaning the MAF and checking vaccum leaks etc.

Jaguar XJR MAP codes are often thrown is there's a dodgy electrical connection on the MAP. It's easy to check.

IME, it won't send you into Limp Home mode. Check and clean everything, and if that doesn't cure it, then get used to clearing it with your £5 dongle once a week!

Cheers

Paul

[Elm Park Royal]

Thanks for the responses, guys.

Really helpful and persuaded me to invest.

Rather bizarrely, the EML dashboard light went out as soon as I put the OBD lead in so I didn't even need to get into the diagnostics to clear it. Further playing around did indicate an historic 0105 code had been lurking. I can hardly wait for it to come back on again!

All the best, and thanks again