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Matt, Mechanical Engineer
Category: Audi
Satisfied Customers: 22729
Experience:  BEng hons Mech engineering, in auto industry 22 years
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Matt. On recent MOT my A3 06 plate sportsback failed on excessive smoke. The garage in

Customer Question

Hi Matt.
On recent MOT my A3 06 plate sportsback failed on excessive smoke. The garage involved used a cleaner and it then passed however the emissions warning light came on a couple of days later and has remained on since. I had only been doing short urban trips and they suggested that it need a longer run at higher revs. I ran the motor on a 200 mile trip (2000-3000 revs in 5th & 6th gears) and the car appeared to respond to normal accelaration input until after about 170 miles and on an incline, I lost power. Changing down from 6th to 5th made no difference, the car would not respond to incresed throttle demand. I have since done more urban driving and the car runs "clean & normal". I have since run an E Scan on the ECU and the following error codes have appeared:
17055 Cyl 1 Glo plug cct - P0671
17057 Cyl 3 Glo plug cct - P0673
18051 Check DTC memory of electrical load controller P1643
16785 EGR system insufficient flow P0401
16618 Boost Pressure Reg limit exceeded P0234.
Submitted: 2 years ago.
Category: Audi
Expert:  Matt replied 2 years ago.
Hello the glow plug circuit faults are likely to be failed glow plugs as they don't last forever and a modern diesel uses them all the time as opposed to just on startup, so I'd suggest replacing them on cyls 1 & 3 as for the other fault I suspect that you have a boost air leakI'd first check all the high pressure hoses post turbo/s for any split hoses or cracked metalpipes, also check the ends of the intercooler as its not unheard of to pop the end caps off under high boost.If this is OK then check the small vacuum lines to the turbo and its connected control solenoid on the bulkhead, any cracks or leaks can give turbo issuesAlso have a feel around with your bare hands with the engine running to see if you can feel any escaping gas under your touch. Another method is to use a soap and water solution sprayed onto any suspect areas - if there's a leak it'll bubble upwith the engine running Also check that the vacuum hose running to the dump /turbo bypass valve is intact with no leaks as if the dump valve is opening prematurely you'll be losing all your boost If this is OK then remove the high pressure intake hose after the turbo and have a feel of the turbine wheel - there should be no play radially at all -but a little bit of axial / end to end float is normal one other possibility is that the wastegate actuator spring has gone soft so allowing the wastegate to open prematurely - if youractuator has a threaded end you can increase the preload on it to see if this improves things otherwise these units are quite cheap compared to a new turbo so it may be worth trying a replacement
Expert:  Matt replied 2 years ago.

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