CEL is on after battery replacement

[Cscameron]

Hi All. Have had the 8 for 9 months now. She’s not spent much time on the road as I’ve needed to do a fair amount of work just to get her road legal after not being brilliantly maintained by the last owner. So far I’ve had a new clutch, all round discs and pads, spark plugs, tyres, throttle body(TPS was shot), full exhaust including cat and yesterday a new battery. Coolant tank and starter motor are next on the list then in theory onto a new paint job if nothing else pops up!

Just need some advice after changing the battery yesterday. Went for the E23 from Tayna after checking the forum for recommendations. Fitted and started fine. Did the DSC reset and the light went straight off. Drove to work this morning (35 miles on the A1M so got a good run) and all was fine. On the way home however the CEL came on as soon as I redlined her and has stayed on. Have started the engine again whilst hot and the oil light was on for a minute as well as the CEL but went back off.

Is there any chance this is the ECU resetting itself or is it more likely I’ve got a new problem to deal with?

It’s a 05 192ps with 77500 miles on the clock. Engine was rebuilt at 60k miles. Premix with castrol p-1. Haven’t done an oil change since I bought her but have only done around 4k miles. Oil looks clean but will do it next week when I change the starter motor. Not sure how relevant any of this is but I’ve quickly learnt you never know with this car!

Thanks for your help

[Ollie]

You should invest in a bluetooth code reader and a decent app (torque or forscan lite) and you'll be able to find out what the EML is.. We can't really take a shot in the dark as it could be almost anything currently..

[Cscameron]

I work for a Ford dealer so will be able to get the code off when I take the car in to do the other bits next week. Was just hoping it was a common thing after replacing the battery that I didn’t know about

[Ollie]

Ah right. Yeah not common... All your dash lights should go out after the initial checks the ECU does (usually you wait for them to go out before you start the car) and then if something pops up even straight after that its fault finding time.

[Cscameron]

Not what I was hoping to hear but not too surprised! I will get more than 50 miles without a problem one day!

Thanks for your help

[warpc0il]

viewtopic.php?f=25&t=43997&hilit=CEL

[PaulAV]

It's possible that with the fuel trims resetting your getting a lean or rich code if there's something not quite right with the MAF for instance, say if it's dirty. But any diagnostics would be purely speculative without the code that it's thrown as there many.

[Cscameron]

Hopefully it will be something simple to fix this time will find out on Monday when I get the code read

[Cscameron]

So had the codes read and I’m getting P0076 and P0103, so MAF and SSV, both of which were replaced about 7 months ago so I know are still good. To add a bit more to the story the valeters at work, who are normally amazing, cleaned the 8 for me and jet washed and shampooed the engine bay. I asked them not to but may have been a minor language barrier. Will give the connectors a blast with some contact cleaner and fingers crossed no more problems

[warpc0il]

Hopefully the problems were just down to water in the connections, which certainly sounds plausible, and only time will tell.

Just note that replacing a component is not guarantee that it's "still good", as a new component is much more likely to fail than an old component that's still within it's normal working lifespan. Was the MAF replaced with a genuine Mazda part or from an alternative source?

[Cscameron]

Yes it is a genuine brand new part. One of the techs had a quick look - restored and drives an RX-7 so is pretty good with these - and he thinks water is most likely the problem but will just have to wait for it to dry out and see. Still driving fine and no drop in power which I would have expected if either parts were faulty/on their way out