EPC and 2 warning lights '03 Golf mk4 1.6 16v

12 May 2014
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United Kingdom
I've got a 2003 VW Golf 1.6 16v MK4 .
I've just had my throttle body cleaned and reset due to a rough idling issue. The idle has improved dramatically and hasn't dipped since.

However, i've got 2 new problems, sod's law.

Firstly if i'm slowing down and drop into a low gear like 2nd it's almost like the car is trying to force the revs back up which naturally fights my braking. This doesn't happen all the time and once im stopped my revs are perfectly calm.

Secondly and most worrying is i get 3 warning lights come up (at the same time) (see attached photo) intermittently. They last for the whole trip once they've come up.
The EPC and the Triangle with ! inside an arrow disappear when the engine is turned off and on again. The other stays on until the engine has been off for a couple of hours.
I have had it scanned and ive had codes

P1176 (o2 sensor 2(post cat?)),
P1553 (something to do with MAF) and
P0171 (Fuel trim or something orother).

These were read in a hurry with a garage in passing as they were fully booked up so didn't get chance to get them to have a proper look.

None of these lights or codes appeared before the throttle body cleaning and as im no mechanic i will try not to assume, but are those codes in any way related to a throttle body?

This only started happening 20 or so miles after picking the car up from the cleaning.

Also had a new tyre but sure that isn't relevant!

Would appreciate any insights, will naturally be dropping off at a garage asap but with a long drive ahead of me i'd like to know what kind of position im in and whether its safe to drive.

I should mention, the second time they came up it was accompanied by an almighty buck but i was rather low revs in 2nd so could just have been struggling to keep up.

The 3rd time it was fine while driving. Came back to it 5 minutes after parking to move it to my favourite spot (sad i know) and came up as soon as i pulled out of the bay.

The photo isn't very clear but all warning lights are yellow/orange, not red.

Thanks very much, Mark

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Here's me wondering what they cleaned the throttle body with.....anyway, the picture of the engine shows that there is an exhaust emissions problem, which is combined with EPC which means a fault code is logged in the engine management system (a combination here, I think).
The warning triangle is a traction control issue - maybe due to the new tyre being fitted, but I don't know why!
These lamps, being yellow, recommend that investigation is necessary but there isn't great cause for alarm at this time.
There is a chance that the emissions issue may cure itself after a decent run, but please be aware these are only my assumptions!
John :)
As above ...................
Might be worth checking that the mechanic got all the vacuum pipes back in place, or one has fractured because of being moved to clean the throttle body. This would account for the lack of control when you let the accelerator off and throw the fault codes. Did you clear them to see if they reappear?
Thanks to both of you for replying!
He'd reset the codes for me, took it for a drive today to see if they'd come back up. Just the Exhaust "emissions workshop" one came up and that was on starting the engine. Took it back to the garage. Typically it had turned itself off :/

I did take his response with a large pinch of salt but he did say being as the throttle body cleaning had been quite a long time coming (had been rough idling terribly enough to stall quite often since i brought the car - 7 months ago) it could just be the odd bugs with it suddenly being clean and functioning better?

He also mentioned if it was a vacuum leak the light's would be constant and not turning themselves off.

Is any of this plausible or have i managed to find yet another cowboy mechanic? Bearing in mind it's quite a big garage and i'd been advised to go there by alot of friends.

I currently have no warning lights up and with a little adjustment to my driving style the high revs when i drop a gear is manageable (as they do go down, just slower)

He did however give me the number for another garage with a smoke machine and they can test for vacuum leaks easier than this garage but he's on over a week waiting list and i have 2 drives 1.5 hours each way i need to know if i can safely make on Monday.
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Oh i should add, the revs only occasionally hold themselves up but only when in gear, never in neutral. Don't know if that makes a difference?
Im recently having the exact same problem
Any information regarding how you got it fixed is greatly appreciated thanks