Engine Light Diagnostic Help - Berkshire - BMW Z4

dangermouse425 · 2 Jan 2013 at 23:16

Hi all,

My yellow engine warning light came on this morning on the Z4. Car seems to be running fine though, no rough idling or spluttering which leads me to believe (after a short internet search) it's a Lambda Sensor that's failed/failing.

Does anyone have a fault code reader in the Berkshire area (Wokingham) and a bit of spare time this week that would be willing to help me diagnose the fault so I don't have to spend £60+VAT on getting a garage to confirm my suspicions? It would be most helpful, as I have a bad feeling I may need to put that £60 towards a large bill in the not-so-distant future.

I've tried using Torque for Android via my OBD2 port, but it says there is no fault.

Forgive me if this is a stupid question, but I recently did a 500mi round trip to York in minging gritted roads in the wet, so is there a chance the sensor has got dirty or something? I read another thread that mentioned the sensor getting blocked.

Lastly, if the sensor does need replacing, what kind of bill am I looking at?

Thanks in advance.

DM

Car Details:
2005 E85 3.0i
~65,000 on the clock.
~7,500 until next service (oil change)
95 RON used for past 18 months of ownership
Passed MOT with no advisories in Dec 2012

[TW]Fox · 3 Jan 2013 at 00:18

It could be almost anything, guessing its a lambda sensor is a bit of a stab in the dark. Is it just the one light thats on?

dangermouse425 · 3 Jan 2013 at 00:45

Yeah, just one light that's on. Yellow engine-shaped one.

Lambda sensor was indeed just a random stab in the dark after a bit of net research. It's just annoying having to pay £60 if they're just going to reset the fault and say they don't know what's wrong with it. Is that likely, or will their computer definitely get an answer?

Brookert · 3 Jan 2013 at 02:37

It will give them a specific code, like p0113 for a specific problem ( Intake Air Temperature Circuit High Input) which they will give to you so you can do some google fu. The first port of call is to reset the light, as a minor glitch can throw an error code, then dissappear.

Most garages will give you the code for free/ or a very minor fee.

Type_R · 3 Jan 2013 at 08:12

Unfortunately I am not close to Reading but have the kit to look up and reset faults. I am sure if you ask on any BMW forums someone will be close by.

Failing that you can get yourself a cable for the PC, it costs £50 via www.BMTechnic.co.uk and comes with all the software to interogate and code your BMW. Well worth the money, especially as your car gets older!

miniyazz · 3 Jan 2013 at 09:47

Minging roads don't make a lambda sensor dirty. Well, not the bit that matters anyway; it's plugged into the exhaust. You can use Torque to monitor the output from the O2 sensors anyway so that might give you an indication of whether it's working as expected. If you've got two banks on your exhaust you might have a second one to compare to.
If your fuel efficiency has worsened it's unlikely to be the post-cat one.

dangermouse425 · 3 Jan 2013 at 11:44

Thanks for the replies, guys. I'll try resetting the light with Torque later today and see if it was a one-off glitch. Are there any risks in doing this?

[TW]Fox · 3 Jan 2013 at 11:58

It's not a one off glitch. It doesnt come on for the sake of it, it comes on to indicate there was at that point something wrong with the car.

Get the codes read properly with kit that can read all the fault code memories, torque isn't really the right tool for the job.

pepsilol · 3 Jan 2013 at 12:12

Not a glitch but it can sometimes be a case where an EML has been fixed but codes have not been cleared with adaptions reset.

[TW]Fox · 3 Jan 2013 at 12:16

pepsilol said:
Not a glitch but it can sometimes be a case where an EML has been fixed but codes have not been cleared with adaptions reset.

I think its probably unlikely that somebody popped round in the middle of the night and fixed his car without him realising though

dangermouse425 · 3 Jan 2013 at 12:26

Brookert said:
The first port of call is to reset the light, as a minor glitch can throw an error code, then dissappear.

[TW]Fox;23481049 said:
Get the codes read properly with kit that can read all the fault code memories, torque isn't really the right tool for the job.

I think, rather than using Torque to reset the code and hope it doesn't come back, I'll pay to have it done properly if no one local has a code-reader. I'll no doubt be back tomorrow with news if I can get it done today.

[TW]Fox · 3 Jan 2013 at 12:28

Are there no OCuk'ers with the right kit in the Reading area? Be a shame to pay for it.

Jez · 3 Jan 2013 at 12:38

Rather than paying out to get the code read, why not use that same money to invest in a cable (and a crap old laptop if you dont have a spare for the garage!)

MatteH Oxford · 3 Jan 2013 at 14:18

I wouldn't recommend that anyone reset fault code(s) etc unless the car has an obvious fault which they are confident of being able to fix.

The poor technician who has to try & fix the fault (when the vehicle owner almost inevitably gives up about 1 week later when the EML light comes on again) will have less evidence and information to go on to fix the issue. Sometimes the car needs to be driven multiple times to replicate the conditions in which the original code(s) was/were set & these may not occur *again before the vehicle is professionally examined. Especially when you have more than one issue, you may only get one error in the time before the technician sees the vehicle, yet originally they may have been 2 or more fault codes. The second issue may crop up until a later point after the vehicle has been 'fixed'.

This isn't a dig at anyone in particular btw. I wouldn't want anyone to pay more for expensive diagnosis time on a car than they have to, and resetting the eml/codes willy-nilly is likely to make people even more inconvenienced if not out of pocket.

Be careful!

Type_R · 3 Jan 2013 at 15:13

MatteH Oxford said:
I wouldn't recommend that anyone reset fault code(s) etc unless the car has an obvious fault which they are confident of being able to fix.

The poor technician who has to try & fix the fault (when the vehicle owner almost inevitably gives up about 1 week later when the EML light comes on again) will have less evidence and information to go on to fix the issue. Sometimes the car needs to be driven multiple times to replicate the conditions in which the original code(s) was/were set & these may not occur before the vehicle is professionally examined. Especially when you have more than one issue, you may only get one error in the time before the technician sees the vehicle, yet originally they may have been 2 or more fault codes. The second issue may crop up until a later point after the vehicle has been 'fixed'.

This isn't a dig at anyone in particular btw. I wouldn't want anyone to pay more for expensive diagnosis time on a car than they have to, and resetting the eml/codes willy-nilly is likely to make people even more inconvenienced if not out of pocket.

Be careful!

Its a simple case of copying and pasting the codes into a notepad file for future reference. Then, if you like me, dumping them in a folder on Dropbox, so they are never far away!

Obviously, before resetting anything one would assume the user knew what the code was and meant.

[TW]Fox · 3 Jan 2013 at 15:16

Matteh is spot on. You don't want it reset, you want it reading to find out what's wrong and reset once its fixed.

Jano · 3 Jan 2013 at 15:38

Haven't seen Rilot posting in a while, but he had a BMW and is quite local to you, no idea if he has the diagnostic stuff though.

Brookert · 3 Jan 2013 at 16:05

[TW]Fox;23482722 said:
Matteh is spot on. You don't want it reset, you want it reading to find out what's wrong and reset once its fixed.

The problem is when you have error codes stored which aren't of relevance to the engine management light being lit. My car for example, had about 5 codes stored for various faults that occured over several years, yet none were enough to set an eml. Silly things like system voltage drop (disconnected the battery) and Maf implausible signal (disconnected it for some tests).

The way to find which problem is the important one is to copy the codes down, clear them, then see which one comes back.

dangermouse425 · 3 Jan 2013 at 16:59

Had the fault checked by a local BMW Indy, the chap said the fault was no longer coming up as present, so could be reset and that might solve the issue.

On the way home I stopped off to fill up with fuel and whilst waiting to pull out of the petrol station, the light came back on.

The fault code was:

GeX · 3 Jan 2013 at 17:10

Intermittent failure of the heater circuit. The heater is high(ish) current draw, so might be showing any slightly corroded wiring. Could always pull the wire off, clean the plug up and WD-40 it. Failing that, replace the sensor.

It'll effect how the car runs when it first starts (as the sensor will be too cold to function), but won't be an issue when it's been running for a bit. Although iirC an unheated sensor will get damaged and fail over time.