I have a mark 2.5 auto on a 51 plate and I love it. Naturally.
My engine management light comes on and stays on unless I leave it and don’t drive it for a few days when it then stays off until I’ve been driving for about 20 mins.
My local garage (who I trust as they’ve worked on a few of my other cars over the last 6 years) say mine is a bit of an odd one as it seems to have two engine management systems - one runs the core functions while the other theoretically ‘learns’ my driving style. The two systems don’t talk to each other (I think they fell out over who gets the last fuse in the box…) and the resulting confusion results in the light coming on. The car feels fine, but its a bit annoying.
Has anyone else had a similar issue? Any thoughts / bits of wisdom / genius ideas that I could look into?
H’mm - intermittent fault? Strange one, usually once the management light comes on, it stays on. IIRC a fault is logged three times, on the third signal it becomes a permanent fault.
Your analysis of the management system is humorous, but not entirely true. The variable part (your driving style) isn’t separate from the main system, it just pertains to a few small aspects of what is overall a permanent program.
Just a thought - do you drive consistently? Possibly there’s a conflict if you don’t, though I don’t really think that’s the answer. Robbies the man you need, and presumably he’s got his head under a bonnet at the moment. Check later!
I drive relatively consistently but now and then I drive a bit more vigorously.
If I drive it everyday the light stays on, but if I leave it to stand for 3 or 4 days (rarely) the light goes off when I start it but then comes back on after 20mins or so.
The chaps at my local garage (HiQ in Ilkeston) have plugged it in and can’t find a fault per se, so I wonder whether a Mazda dealer would have more advanced equipment that may come up with something.
0DB2 socket is part of the fuse box, not below it. R/H side, vertical mount. Mildly annoying as if you leave a code reader plugged in, you can’t refit the fuse box cover. I bought a Scangauge several years ago, which reads parameters you can set, but if you want to keep viewing them, you have to keep it plugged in. Unfortunately left it in the car one winter, and it now appears to be useless.
BTW - if you buy a code reader, make sure it will read Jap codes, some won’t. Not always easy to find this on ebay, or amazon, so better to check back with the maker first. I’ve been looking myself - always a handy tool to have, but I can’t decide between cheap and expensive, they aren’t all suitable. Some only state they read ‘common codes’ - which means american and/or european ones, not japanese.
You did say your local garage ‘plugged in’ so I assume they used a code reader? The fault needs to be present (indicated on the management light) or you won’t read anything. Plug it in first, then switch the ignition on. Preferably start the engine, or there may be a risk of burning out an ignition coil. On a Mk2/2.5 not sure about this, but better safe than sorry.
It might even be a partial fault on the light itself, as it goes off when you haven’t used the car, but comes on when you’re driving, Could be the return wire is shorting to ground as you drive (car movement) but remains O/K when static. Not easy to check wiring on an NB - or any car today, but if that’s the problem then you could be spending money chasing shadows.
My NB manual doesn’t cover auto trans, so it might be a fault there, but I can’t comment on that - sorry.
Thanks very much - that’s very helpful, I hadn’t thought about Japanese vs European and US codes. If you, or if anyone else, finds one that does that which you would recommend, please let me know?
The problem with burning out the coil packs was not on the Mk2.5 as the original poster advised his car is. It can happen with the Mk2 but that is if you leave the ignition on overnight not to check for fault codes that takes say 10 minutes at most.
Plenty people here have purchased cheap code readers that work do not go on abhere out your lack of decision making.
The ODB2 codes are a standard and are not Jap or European as only the £120 plus readers have an offical impoter in the UK, the original poster will not be able to talk to the manufactuer of the code reader to ask them questions, I have used a good number of different cheepo code readers on the Mk2.5 and they all read the codes on a Mk2.5.
Any specific codes that are not on the standard ODB2 listing will only show on expensive specific code readers. These will cost well north of £250 and are not of use to the op but are for very specific tasks like telling BMW cars the handbrake has been rest or in certain cars they allow access to the security system to code keys on to the car
For the original poster lift the carpet on the passenger side of the car, do not just feel the carpet.
When you lift the carpet you will see a metal cover over the ECU at the font bulkhead / firewall. It will have wires going into it.
If there is any rust staining or dampness / water present in the early stages of that problem you can get the engine warning light on with no codes registering.
In this cae you disconnect the battery and get the area dried out and get the rear cabin drains unblocked.
Have you checked the fluid levels in the AT torque converter? If low it can eventually overheat, but could easily take up to twenty minutes depending on how you drive. There should be a code for this.
A friend’s BMW was causing grief in a similar way last year, none of the reported codes made sense, and it was only the mechanic noticing a tiny weep underneath on the housing that managed to sort it.
Cheap code reader = Maxiscan MS309, available for under £10. I have used mine several times and very happy.
Unfortunately this problem does sound like ECU, especially if there is no running issue with the car.
The MK2.5 in particular also seems to get more damp issues in the area of the connector plugs on the ecu. If there is a problem you may find that the three plugs are difficult to remove from the ecu and there is evidence of dullness/corrosion on the ecu connector pins that are normally shiny.
Whenever I supply kits to replace these ECUs, the plugs are an afterthought. It is possible that if caught early, the plugs could be replaced and the more expensive ECU and associated parts saved. If there is corrosion on the ECU pins it, I would advise replacing the affected plugs anyway.
A customer recently did a really good job of this and at some stage I will put some pictures up. The contentious issue is how to solder these wires together as many different ways.
Hopefully wrong about the ECU but very easy to check as corrosion very obvious.
