Emission And Engine Management Light On

[Leewill]

Hi people just after a bit of advise,
I`ve got a 2006 A4 Avant TDI (170), on a long trip last week, the glow plug light started flashing, then after about 15 miles the engine light came on, can`t remember which light is emissions and which is engine management, but anyway, slight loss of power not going over 3000 RPM, so I pulled over switched her off and let her have a breather, then got full power back with just the engine light on.

So booked her in to an independent garage for diagnostics, they said loads of faults came up so they cleared them, and because on test they couldn`t get the light to come back on, to drive it and as soon as the light comes back on, bring it straight back, after seven days the glow plug light started flashing again so I took it back again.

They said two faults have come up, throttle body, and MAF meter, and that they thought it was the throttle body, £400 notes plus labour, and if that didn`t cure it, they`d have to then replace the MAF meter.

When I asked how much the MAF meter was they said about the same price, but they were 80% sure it was the throttle body.

My dilemma is this, I used to be a car mechanic years ago with not such advanced electronics on the motors back then, but I priced up the parts at a motor factors, Bosch parts that are fitted to my motor, just doesn`t come in a Audi box, £150 plus VAT for the throttle body, £58 plus VAT for the MAF meter, they had the MAF on the shelf so I bought it and fitted it, drove it like a joyrider for an hour and it`s mint, my thinking and how I used to diagnose problems back then was go for the cheapest option first, but the guy in the garage wasn`t having any of it.

I`ve got it booked in for the throttle body change on Thursday, (this was before I priced up the MAF and fitted it), with my £150 part, do you think this guy was just trying to have my pants down, or just made the wrong educated guess, or is it that its not fixed and the light may come back on, don`t want to replace any parts if it`s not necessary, the guy seemed really nice and he didn`t charge me for the two diagnostic plug in he did, don`t know if I should see how it goes or take it back to him, I`d fit it myself but I`ve read you have to align the throttle body with diagnostics, any thoughts would be helpful.

 

[Imola-S3]

That bloke is having your pants down mate.

Most definitely.

MAF Sensor should be the first thing to change - DEFINITE NOT THE THROTTLE BODY!

And you can change a MAF Sensor yourself... its one of the simpler jobs to do on most cars.

This bloke is doing you all these freebie favours to suck you in and make you trust him and his word.
DO NOT TAKE YOUR CAR TO THIS BLOKE.

My Dad met a mechanic like this a few years ago when his S3 was fetching up a few fault codes which kept putting the car into limp mode.

He tried to get my Dad to have a full bottom end rebuild at £700+, plus told him he needed his car remapping again. Turns out all his car needed was a coolant temp sensor, thermostat and a new MAF. He ended up getting the remap done by this bloke (which was intentionally set up badly so that my Dad would take his car back with more new codes) but after taking the car to another place he got it mapped again and everything's running spot on now - with another 15,000 or so miles on the clock.

This bloke is ripping you off and a throttle body will not rectify this problem without the MAF being done first... the MAF is cheaper and they are more prone to failing and causing the issues you're experiencing than a dodgy throttle body.

I hope you take my advice. I'd hate to see another dodgy conman mechanic take someone for a ride and there still be no joy at the end of it.

 

[Imola-S3]

Having re-read the bottom of your post again I've seen that you've already done the MAF and that seems to have corrected it.

From my experience, a faulty MAF can trigger off fault codes further along the line with other sensors + parts because they'll be reading different figures to what the MAF is.

I still wouldn't trust that garage. A throttle body isn't a difficult job to take on... so for him to want £400 for a £160 part + charge labour I'd be extremely wary.

Most people will just fall for his act and pay up... you on the other hand having previous experience knew slightly better and that so far seems to have paid off.

Just because a code reader says there's a fault with a specific component it doesn't mean it should be replaced.

Especially since there was a MAF related fault code (meaning that part definitely needed to be replaced based on the cars symptoms).
He went for the big bucks and this time it didn't pay off.

Cancel the job with him... hold on to your throttle body for a little longer... if the problem comes back then by all means find a garage to fit it for a reasonable price... but if not - see if you can return the part or stick it on eBAY.

 

[Oranoco]

Bit like the garage diagnosing a dead diesel pump on my mates old Corsa Combo and quoting £1200 to sort it. My brother stripped the pumps control box and resoldered a couple of joints and the van started and has done another 30k miles. Not bad for a free repair

 

[Imola-S3]

Worse thing about that is.... that garage would probably have done the same thing. Easy money.