Engine warning light on :-(

[bramley]

2003 530i, engine light is on (not EML) and the manual says:

"Deterioration of exhaust emission control values. Have the problem examined by BMW service"

Anyone else had this or got a hunch as to what the problem might be? Can i read a fault code without a special gadget?

We've got a manic week coming up and we need to use the car everyday, only short journeys at < 60mph though. Bad idea doing that before it's looked at?

Could it be the cat?

Any thoughts welcome...ta

[Sport Coupe]

It will not be the CAT causing the problem but it might be slightly effected by a rich mixture if run for too long with the issue not being fixed.

It could be a number of things really but in my opinion the main culprits could be:

Lambda Sensor/s
Coil Pack
Air Mass Meter

Are there any other side effects you are experiencing such as engine stalling,fluctuating idle, flat spots, poor MPG e.t.c. ?

[dan101smith]

Had this on a Z4, turned out to be a lambda sensor.

[TheEnd]

Loads of things will cause this light, you'd need to get it on diagnostics first. I've seen it on from little things like loose oil filler caps

[BIG BAVARIAN]

mine came on 3 times last year,1/ lambda sensor 2/breather pipe blocked 3/no fault showed up ,cleared i.e (light put out) ,then ok after that,

[SJobson]

Are you sure it's not the EML, Dave?

I managed to get mine to come on by nearly running out of petrol and spluttering to the garage to fill up. It took a while to go out, about 2 weeks I think. You are unlikely to cause any serious harm running with it on, but it may cut power etc, so worth getting the fault codes read to see what it is. MAF sensor is my guess but it could be lambda sensors, dodgy fuel, or all sorts of things.

[bramley]

I haven't seen it yet Simon, I'm too drunk to risk going out there with the keys now! The wife's seen the manual and confirmed it as the engine light rather than EML. Apparently it's running fine and idling fine (and certainly has been recently). I'll take it for a spin tomorrow and see what it's like. Fingers crossed it won't be expensive whatever it is. Last fill up was at Waitrose and although the fuel light was on before that it wasn't that low. MPG recently has been around 17mpg after lots of short journeys round town with a heavy foot, rising to 24mpg on my trip to Wales which was also with a heavy right foot so I didn't think that was too bad.

Thanks for the replies folks, will see what it's like tomorrow.

[ian in lancs]

Lambda sensor - had two fail on my Z4M. I don't think lots of short journeys without the engine warming up properly do it much good.

[bramley]

The light has gone out!! Drove it earlier (with the light on) and it idled and drove 100%, stopped at the inlaws, got back in to drive home and the light had gone off.

Any bets as to how soon it comes back on?!

[bramley]

It's back on!

[HRG]

Check the fuel cap!

Happened on my 528I recently and I took it to BMW to diagnose. In my case it was two split pipes, one from the air filter to the manifold and the vacuum pipe which hides under the engine cover. The diagnosis cost £30, if I'm honest I'd have probably replaced sensor after sensor and it would have cost me loads more to track down.

Money well spent IMO.

[bramley]

HRG said:

Check the fuel cap!

Happened on my 528I recently and I took it to BMW to diagnose. In my case it was two split pipes, one from the air filter to the manifold and the vacuum pipe which hides under the engine cover. The diagnosis cost £30, if I'm honest I'd have probably replaced sensor after sensor and it would have cost me loads more to track down.

Money well spent IMO.

Fuel cap seems ok, but the design of them means it's hard to guage how well it's sealing? Gonna have to get a diagnostic check done.

[HRG]

It *should* go out of it's own accord once you cure the fault, however mine took a couple of days as the reason it was on is the long term map was running to rich. Once the fault was cured it took a little while for it to average back down!

[jonny996]

This happened on mine, indy asked if I had let it run low on fuel, YES, well dont he replied, put in some injector cleaner & told me to run it on V power for a month, 2 months later it went out, I was begining to call him names, but hayho he knew his stuff

[bramley]

my local garage read the fault code today and it was triggered by the lambda sensors. However, they monitored the real-time values from the sensors with the engine running and they were both giving normal readings. They suspect the cars been through a big puddle and got some water in the sensors which shorted them?? Anyway, they've cleared the fault code and I'll see if the light comes back on.

As an aside, after the floods last year here, they were swamped lol with cars that had the engine warning light come on due to water in the sensors. All local parts suppliers sold out of lambda sensors, yet this garage simply took them out, cleaned, dried and put back and they were fine apparently, didn't need replacing.

I needed all 4 wheels balancing due to the incompetence of a well-known fast fit tyre place cocking the balancing up, and they only charged me £20 for everything so I'm happy, although there is a chance the light will come back on.

[ian in lancs]

There's a thread running about this here

http://www.pistonheads.com/gassing/topic.asp?h=0&a...

Ian

[bazking69]

Lambda sensor would be my first port of call. Mine had no symptoms apart from slowly trickling down from averaging 23MPG to about 17MPH. New sensor, 25MPG on the same journey.