Downshift sudden and complete loss of power from 100km/h Audi A3 2.0T (PQ35, DQ250)

[toml]

Hello all,

I have just purchased a second hand Audi A3 2.0T 8P which has been my dream for a little while now. Love the car but have got a serious problem with it that I need help on, you guys have the most experience from my google research.

The problem started like this - Driving along for an hour at 100km/h with cruise control set when I hit a hill on the highway. While climbing the hill the gearbox kicked down a gear into 5th and accelerated to maintain 100km/h. The moment 100km/h was reached and the car stopped accelerating, the 'ESP' dash light stayed solid, the car reduced to idle, all engine power was lost and the throttle was unresponsive. A restart fixed the malfunction. (In the middle of the highway, it was a terrifying experience)

I was able to replicate the malfunction on a steep hill at lower speeds in the following way: cruise control set to 50km/h, engine hot, let car slow to 45km/h, trigger downshift, car accelerates to 50km/h, acceleration stops (slight deceleration), 'ESP' Light, no power. At idle, in a safe place I was able to keep the car in it's no power state, the car wouldn't rev past 1600RPM. The car sounded like it was not firing on all cylinders but maintained idle ok.

I'm curious, has anyone else experienced these exact symptoms in this car or a car on the platform? I would be very grateful to find out what caused the problem and how it was able to be fixed!

Thanks all,
Tom

Car Information
Make:	Audi
Model:	A3
Version:	8P (2003-2012)
Year:	2005
Engine Type:	2.0 TFSI, 1,984 cc (121 cu in) I4, "AXX" 200PS (147kW; 197hp) @5100-6000, 280 N·m (207 lb·ft) @1800–5000, 2004–2008
Gearbox Type:	DQ250, (6 Speed DSG)
Platform:	VW A5 (PQ35)
Other Cars on Platform:	Audi A3 Mk2 (8P)
	Audi TT Mk2 (8J)[1]
	Volkswagen Touran (1T)
	Volkswagen Caddy (2K)
	SEAT Altea (5P)
	Volkswagen Golf Mk5 (1K)
	Škoda Octavia Mk2 (1Z)
	Volkswagen Golf Plus (5M)
	SEAT Toledo Mk3 (5P)
	Volkswagen Jetta Mk5 (1K)
	SEAT León Mk2 (1P)
	Volkswagen Tiguan (5N)
	Volkswagen Scirocco (13)
	Volkswagen Golf Mk6 (5K)
	Škoda Yeti (5L)
	Volkswagen New Compact Sedan (1K), (16)
	Audi Q3 (8U)
	Volkswagen Beetle (A5) (16)\
	Volkswagen Eos

[Guest 2]

Have you had the car scanned with VCDS?

[toml]

Have you had the car scanned with VCDS?

I went and got a reading today, the results were too noisy with many faults recorded from a blown control unit fuse (unrelated, resolved) so were no help.

I'll replicate the malfunction and get back to the diagnostics ASAP.

[toml]

Ok so here is what the diagnostics gave me:

Motoronic MED9	4
P0238	Boost Pressure Sensor	Signal too high
P0601	Control Unit	Component Defective
P0441	Evaporative Emission Regeneration System	Flow Rate Faulty
P1335	Engine Torque Monitoring 2	Above Control Limit
ESP Teves Mk60.1	1
0522	Engine control unit	Read out Fault Memory
Airbag AB 9.4	1
0525	Instrument Cluster	No Signal
Gateway 3.0	1
0514	Navigation System	No Signal
0517	Transmitter/receiver unit for telephone	No Signal
Audio	Fault

Can anyone wiser then me see what's causing it?

[toml]

This is the best day I have ever had.

Smashed some work at uni today the found myself back on this problem. I started by trawling through forums creating a troubleshooting document for the codes. Realised a good place to start would be the G31 Boost Sensor, figured I would take a look at the old one, found some very clear instructions here. Get to the car head torch on.

I found the sensor was unplugged! Now it's fixed! Seriously! How simple! One of life's little blessings. The little things I love.

Anyway, for anyone in the future suffering with the exact codes, hope this helps as a trouble shooter even if it's just to tick one thing off the list.

Another symptom I now know is the car being low on power (I didn't realise this as the car was new to me). How she goes now!

Anyway, night time here in Aus. Night all, thanks Chris for your reply and thanks to all that had a look!