Hello,

Firstly I'm writing this on my iPhone so sorry for any stupid spelling changes/mistakes.

This is the last chance for my Audi a4 cabriolet.

Problem: yellow engine block light is on constantly and so is the yellow ESP light (exclamation mark with circle arrow around it). Power is on the sluggish side not limp mode but down on power.

What action have I taken: taken it to a mechanic, who has replaced maf and abs sensors. He cleared the codes and it ran great, turn the engine of and back on again and the codes came back???

Other: rear right brake light, replaced bulb and it worked for a while then stopped, replace the loom still no rear brake light. 

My conclusion: looking on line some forums recommend replacing the brake light switch as this can affect the abs hence the light and why the rear brake light doesn't work. 

Can anyone shed some light (excuse the pun) on this. 

Thanks in advance!

Do you remember what the fault codes were?  Also, what engine does your car have?

Hi benjie,

Thanks for your reply. 

Its a 1.8t, I had written the codes down but I left it in the car, so I don't have it to hand. It did have an airflow code but it's just had a new maf and both lights still come on? I'll be getting the car back tomorrow fixed or not, as the mechanic has pretty much tried everything. The thread below titled "dash lights" I think, the OP had similar lights but was fixed with a new maf? Ahhhhhhh! 

OK, well maybe try and get the codes cleared and then go for a drive.  Rescan the car after that then you'll know which codes are current.  Then go from there.

 And post up the codes to here

Thanks guys, pick it up today. New maf, new abs sensor and the engine block and ESP lights are still on?! 

Just to add, the mechanic clears the codes, engine light and ESP light go and temp gauge works. Goes or a drive turns engine off, restarts and codes come back and gauge does not work? 

I give up with this car. 

Ok, got the car back. Scanned it with my cheapo scanner came back with 2 codes

16487 (maf I believe? But its just had a new one?)

17544 help with this one? 

Scanning with vagcom tomorrow. 

16487/P0103/000259 - Mass Air Flow (MAF) (G70): Signal too High

Possible Symptoms

• Probably no serious malfunctions
• Loss of power

Possible Causes

• Wiring and/or connections (short circuit?)
• Mass Air Flow (MAF) (G70) defective

Possible Solutions

• Check wiring and connections
• Check / Replace Mass Air Flow (MAF) (G70) 

Was the Maf a OEM audi Vw part? If not id get it changed for a genuine one. The wiring needs to be checked aswell as it could be a bad connection.

17544/P1136/004406 - Fuel Trim: Bank 1 (Add): System too Lean

Possible Solutions

• Check Mass Air Flow (MAF) Sensor
• Check Fuel Pressure Regulator
• Check Fuel Pump
• Check Intake/Exhaust System for Leaks
• Check Secondary Air Injection for Leaks
• Check Vacuum Lines for Leaks

Id say this fault will go once the maf problem is sorted

 Your car if its not remapped should see 120-125 g/s on full throttle at max bhp range - 5-6k rpm

Edit: and at idle you should see from 1-25 g/s

 Heres a maf log on a 2.0T with 310 odd bhp but it gives the idea of the pattern of the figures

Thanks steveee! I cleared the codes earlier and will take it for a drive tomorrow, see what comes back. 

Vagcom tomorrow. 

Stevee:

 

Id say this fault will go once the maf problem is sorted

He's had a new maf though?

Bowen - have you checked the connections to the MAF as (I think) they're at quite a tight angle.  Pretty sure the ESP light will go off when the MAF is ok.  It's worth noting that, with the battery connected, if you unplug the MAF it will automatically store the fault code.  In my partner's VW Polo, when I changed the MAF, the light stayed on and the car was down on power (despite having a brand new MAF) until I cleared the fault code from the car.  Then it was fine - could this have happened to you?

Can I just add - look at the contacts that the brake light bulb sits in, make sure they're not corroded or rusty.  If they are, give them a bit of a rub with an abrasive.  They've been known to give errors if in this state.

Here's the info about the other fault code -

16487/P0103/000259 - Mass Air Flow (MAF) (G70): Signal too High

Possible Symptoms

• Probably no serious malfunctions
• Loss of power

Possible Causes

• Wiring and/or connections (short circuit?)
• Mass Air Flow (MAF) (G70) defective

Possible Solutions

• Check wiring and connections
• Check / Replace Mass Air Flow (MAF) (G70)

Right had it vagcom'd.

Clear two codes, maf and intermittent signal to temp sender and the codes come back instantly?! 

The temp gauge worked last night and it ran great this morning no temp gauge and runs like crap. As the codes come back instantly, I think there must be a wiring proble somewhere? 

 Itll be the maf or the maf wiring. New mafs have a warranty as not always perfect.

 i aslo had a code come on vagcom Open circuit short to ground?

Next step is call an auto electrician, just wondering has anyone had this problem before.

Thanks again guys!

 it makes abit more sense now that i saw short to ground. Thanks for your help stevee

 Just read my posts a bit scatty as i was typing using my iphone.

Ok quick round up; from what i can recall

1.maf signal too high

2.17544 system too lean

3.short to gound coolant temp sensor

Thanks for all your help this far guys. Calling around a few auto electricians in my area now to get it booked in.

 to keep you all updated.

I unpluged the maf last night, took it for a drive and it drove like a dream holds boost much better. I know this is by no means a fix but more of a test.

Its going into an auto electrician tonight.

Itll be a bad new maf or the plug into the maf

Ok, so I dropped it in to the auto electrician "2 snapped wires in the to the maf" all fixed pulls like a train! Thanks for all your help again! 

However, I drive around 20 miles today and the engine block light came on scanned it. Two codes are back 17545 and 17536?  Fuel system too lean and too rich? Is that correct for those codes?! If so how?! 

Writting this on my iPhone again, sorry for spelling and grammer. 

Cheers. 

 Do you have the old maf still that you could put that back in? Is it a Audi maf?

A bad maf would give those results. Or a vacuum leak on a hose in the engine bay. Check the vacuum lines around the airbox housing and any vacuum lines you can see. If you still had the old maf id swap that back as it might of been perfect and just the wiring at fault, and now the new maf might be off

Cheers stevee, I'll try that. Thanks again for all your help and benjie I owe you both a pint. Will let you know how I get on tomorrow. 

Good stuff hopefully youll get it sorted

Another thing when I start it from cold it idles higher 1.5k then after day 1 minute it drops? This car is so confusing! 

next to the airbox is a small circular valve with 3 vacuum tubes , inside is a small plastic type diaphragm on a spring , the top inlet tends to snap or the spring gives way . As you open an close throttle the valve operates . If its u/s it will cause a higher idle speed and poor/rough acceleration , it will give a too low lean reading . I haven`t got the part number but it is on etka , its worth giving it a kwik going over so as to discount it .

 Hi Rich,

Are you refering to the crankcase breather valve? Doing some googling it comes up with quite often. I also out my ear next to the airbox last night and could some thing like air whooshing/escaping.

images would be great!

 Hello Gents,

I want to keep my problems in one place and not create needless threads.

Where can i get a check valve? Is this audi dealer only?

http://www.urotuning.com/shop/vacuum-check-valve-a4passat-18t-p-2489.html

i know i could buy it from there but it may take a while coming from the states.

cheers

 ok, after another visit to an autolec, the maf is in and working, as is the temp sender.

Now i have a new code: 16991 and 17545?

Idle higher than expected and running lean!

Now i think its a boost leak somewhere, your thoughts?

thanks,

bowen:

 Hello Gents,

I want to keep my problems in one place and not create needless threads.

Where can i get a check valve? Is this audi dealer only?

http://www.urotuning.com/shop/vacuum-check-valve-a4passat-18t-p-2489.html

i know i could buy it from there but it may take a while coming from the states.

 

cheers

 

woah , i did write more lol , thats the one for your 1.8T , the one i desribed is for 2litre 20v non turbo , check some of the suppliers on the forum 1st , they do tend to be Dealer only bits , but because they tend to fail quite regular i`m sure GSF or similar could supply :)

If you want a job done do it yourself! Bought a crankcase breather valve from Audi £8, fitting 20mins. Job done, high idle code gone and lean running code gone! Pulls much better! I'm still hunting down any more possible boost leaks too! Anyone know where the dv is? BFB engine code? 

Thanks for everyone's help once again! 

Ok after replacing the crankcase breather, where before there was suction thought the oil cap there is now air blowing out? Is this normal?!

And codes 17545 and 17536 are back. 

looks like a slow process of elimination ,,, check all hoses , wiring , terminals , sensors etc , another turbo member should be able to point you in the right direction :)

Did you try the old maf yet? In my opinion they are normally maf codes, either that or a fuel pressure regulator messing up. Or a lambda.

i was gonna suggest checking lambda next Stevee

Right, in an effort to keep my problems in one place;

Since replacing my crankcase breather valve; I still get running rich and lean codes. I also have a really rough idle worse after changing the breather valve. 

As an aside, when starting the car I get the (!) BRAKES warning light and finally my climate control panel is dead. Uhhhhhhh I think that's it.

Where to start....