P0720 and P0600 and Limp Mode
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Junior Member
Joined: Mar 2007
Posts: 25
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From: NJ
'11 GL350, '03 Audi A4 Avant 1.8T
P0720 and P0600 and Limp Mode
Last weekend while driving Big Silvy (yes, that's my truck, an '02 ML320 with 97500 miles), all of a sudden I got 5 warning lights on the dash: BAS/ESP, ETS, ABS, BRAKE PAD WARNING (0), and E-BRAKE. It went to limp mode. While stopped at a red light, I switched off the ignition and restarted the engine. Everything went away and the truck drove normally, shifting as it should, no unusual noise, perfect. Then, coasting to a stop at another light, I got all five warning lights again. This time I got the CEL. I didn't have the time to do the switch off-and-on cycle as the light turned green but the gear was stuck at first and when I gave it more gas the truck shuddered. I had to stop at the shoulder stop the truck, wait a couple of minutes then switched back on. Everything went back to normal. I was able to drive home without the problem re-occurring (about 5 minute drive). I haven't driven the truck again but I couldn't take a chance of driving it for safety concerns. I used a generic OBD2 reader and VAG-COM using the OBD2 mode and both gave me the codes P0720 (Output Shaft Speed Sensor Circuit) and P0600 (Serial Communication Link). Any ideas? Please help.
Thread Starter
Junior Member
Joined: Mar 2007
Posts: 25
Likes: 0
From: NJ
'11 GL350, '03 Audi A4 Avant 1.8T
Update
I'm at the dealership and was told that there's oil in the TCU, big bucks to replace but they have to take apart the transmission to investigate if it really needs replacement, about $2K to replace. Sounds right or rip off? I'm being charged $315 just to diagnose... 
Thread Starter
Junior Member
Joined: Mar 2007
Posts: 25
Likes: 0
From: NJ
'11 GL350, '03 Audi A4 Avant 1.8T
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