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MG MGF Technical - Engine Management Warning Light

Been a while since I posted anything on the BBS, mainly due to other interests taking more of my time but I also bought a new car back in March. I got myself a Mazda MX-5 whihc is great, but I still have my MG TF160.

Anyway, hello to anyone that may remember me and hello to those of you that don't! ;-)

Right, getting to the point...

I left my TF parked outside over the Christmas period and did not use/start it for about 2 weeks. I Went to use it on Monday, started no problem, cleared the windows and got back in to drive away only to notice the amber engine light was on (solid not flashing). I switched off, waited for a moment then tried again - light still on.

I've tried it since and even drove the car a few miles. The light still stays on but the car is driving fine. Coolant and oil levels are ok and the car reaches normal operating temps as expected. The only thing I noticed was that the engine seemed to turn over a little slower when I started it, not surprising given the recent weather and that the car had sat for two weeks without being started.

Anyway, has anyone got any ideas as to what may be the cause? Unfortuntely the TF is starting to feel like a money pit against the 5. :(


Paul L.
Paul Lathwell

Hi, Paul. A blast from the past! Are you still running dotcomoff?

Is it the engine management light that is glowing, or the battery charge light? If its the latter, then is may be that the battery or alternator is on its way out. It might also be a damaged auxiliary belt - if this snaps it can get caught in the cam belt. :(

If its the engine management light, you need to connect a diagnostic computer to it to get the error code, which will indicate the problem.

Ralph Gadsby

I've seen a MEMS3/160 ECU do this before after a laid-up period, a long time ago so my memory may not be reliable... I disconnected the battery and left the ECU unpowered for a day or so, then reconnected, and the light didn't re-appear. The coil packs on that engine were beginning to fail, so I put it down to condensation on the ignition circuit exacerbating an already weak spark and the ECU detecting unburnt fuel at the CAT.

I've also seen a weird and wonderful array of warning lights from a battery that was on its last legs - along with slow cranking of the engine - so an overnight charge of the battery off the car would be my first step, before opening the wallet again for a TestBook interrogation.

Hi Ralph,

Well the website still exists, but I rarely look at it these days let alone make any changes. The last thing I put on there was a few pics of my new MX-5.

It's an amber warning light showing the engine and although the car appears to be running fine, it is starting to seem like a trip to the dealer's will be necessary to identify the cause. :(


Thanks for the info, I may have to give that a try - if I can find the will-power to go out in the cold to do it that is! It's all to easy to be lazy and just use the MX-5 instead! lol. ;-)


Paul Lathwell

An Amber Warning is only a 'Caution' to be fixed at next Service so you do not have to put up with driving the MX.
The Lambda (Oxygen) sensors are the common 'failure' so for a 1st, check that they (2 on your car) have not frayed cables and clean the connectors to remove any damp.
NB. New Sensors vary from X-Part 135 to 35 for Bosch with the need to change the connector.
Geoff F.
Geoff Farthing

>An Amber Warning is only a 'Caution' to be fixed at next Service so you do not have to put up with driving the MX.

Well I certainly would not call it "put up with driving the MX". LOL! The MX-5 is a great car as is the F/TF. Both have their good and not so good points, which I suppose is one of the reasons I still have the TF despite it's numerous flaws.

Thanks for the heads up with regards to the warning light. I think I may well just keep using the TF as I was before and hope it does not get worse before it's service which is due at the end of March. I could always book it in a couple of weeks early I suppose. ;-)


Paul Lathwell

Talking of oxygen sensors causing the warning light to come on....

Some time ago we had a customer come in to our workshop with the engine light on. Investigation showed that it was a problem with the cat. This was quite obvious, due the the hairs on the exhaust manifold where it had been sleeping and had disturbed the plug for the O2 sensor!
Ralph Gadsby

Hi Paul,

Funny you should say that I have exactly the same problem on my mgtf. This occurred about 2 weeks ago.

Car running fine, had a service about 3 months ago. As you say only wee issue is the starting.

Wheras before you got in car and turn key it fires straight away, however, I noticed that it's now a tad sluggish. When you turn the key in the very first half second rather than "Brmmm Brmmm" its as if its not going to start or that the battery is slightly flat, so it gives the sound very briefly that you think "Ooops not going to start" but it in the same second (but latter half) starts straight away.

However, my engine management light is on an stays on. Everything else if fine, no red charging lamp or anything, car runs fine, oil fine and water fine.

So if you get to the bottom of it let me know. I'll try the trick of disconnecting battery and then reconnecting to see if light will go off, otherwise its a trip to Vauxhall ( they took over old MG garage) to see testbook. Tried AA and the guys said that AA disg unit won't read the socket in fuse box under the steering wheel as quote "Rover swapped over two pin connections, so AA unit can't read"


Hi Brian,

Having since driven my TF the battery seems to be charged up again and is once again turning over normally when I start it up. Basically the only "problem" as such is the fact that the warning light is on, I really cannot detect any other faults with the car suggesting there may be a problem.

Chances are that unless I experience further problems I may just well leave it until I take it in for it's annual service in March.

If you do try the trick of disconnecting the battery please do let me know if it cured the problem. I may give it a go too. ;-)
Paul Lathwell

This thread was discussed between 09/01/2009 and 12/01/2009

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