Help- recurrent engine warning light
 

I have a UK 2004 Mazda RXQ 231, bought second hand at 18000 on the clock dec 2008. only done 31 000 now. every month or two the engine warning light comes on and stays on. sometimes when it starts or just mid driving, but never the same way twice. i have taken it back under warranty to mazda since it was bought from a dealer, 7x in the last year and they still havent found a problem. every time it goes back they put it on the computer and find nothing and just reset it only for it to come back a month later. i reg check the oil, and when the light is on the car seems to run fine.

they once tried to change something with the exhaust warning light and that failed. but mostly nothing happens when they put it on the computer.

it happened pretty much the week after i bought it off them , but it only had one previous owner who was an old man who only drove it on weekends for 4 years.

mazda tried ringing their regional manager but nothing seems to have worked.

please can anyone suggest an explanation. Im not getting anywhere and getting fed up now, since its out of warranty now and only got it back last month after they tried changing an exhaust sensor and that did nothing. if it keeps happening im going to have to sell it cause im going spare

Seems like an odd reason to sell your 8. It might be something quite minor.

You could try connecting the ECU to your laptop (assuming you have one!) to check for error codes while the problem is occuring (i.e. whilst the light is on).

You need to figure out what the code is...then we can help you

It could be anything from a fubarred gas cap and an emissions code....to a missfire code...or a stuck intake valve

At least if we know the code we can try and figure it out

If it isn't throwing a code...it's going to be fun to figure it out via the internet

Does the car run normally with the CEL on.....??

By the way, this might be a silly question but are you sure it's the 'check engine' light coming on? I have a UK 231 and I often get the 'coolant level warning' light whilst i'm driving. I think it's a common problem with the UK spec cars, but it's a sensor fault, rather than a mechanical problem.

That's a common problem pretty everywhere :)
That is the red "temple" shaped light though.
As for the CEL, it should record the code unless you reset it.

thanks,
im not an expert or in anyway used to dealing with cars to be honest.
how do i and where do i connect it up to a laptop? i must need some sort of program / drivers or something to access it no? i cant imagine its just like plugging it into a USB?

You need an OBDII\Can reader with an appropriate software :)
It's not a big expense and works on most modern cars, a quick search will give you some good results!

As specialpowers pointed out though.. is it a CEL (yellow, engine light) or a red light? Since you say you aren't an expert then you may be misunderstanding the warning lights :)

its definately the yellow engine warning light. the coolant is a completely different light - im not that much of a noob!

where do u connect this stuff up to the ECU?

Under the steering wheel :)

OBD II Data Link Connector (DLC)

http://www.myrotarycar.com/portal/fo...E0102W0094.png

I have found the code thats been causing the problem.

P0172 fuel trim too rich bank 1

ran a live thing and it showed that the short bank 1 sensor wasnt working. something about an open loop happening when the car is running

i think this was the same part that was replaced a month ago!

y is this happening? do i have to replace it again?

HO2 sensor or fuel pump issue, pressure or bad unit

Do you red line it?

Only occassionally on the motorway. mostly urban driving and it never comes on on the motorway, usually in town around london