P0638 - CBEA Engine

Bill1975

Active member
Joined
Jan 3, 2020
Location
Richardson, TX
TDI
2011 A3 CBEA
2011 A3 - 89,000 miles. This is my first TDI so pardon my ignorance if I'm missing a few things.

Tonight the CEL came on, and glow plug light started flashing. VCDS returned a P0638 code. I read some posts and saw this video which describes cleaning the throttle body (I know its not an actual throttle body) and EGR tube above it. I can certainly try cleaning it, but I'm wondering if it's an electrical problem with the unit itself? I ask this because:

1) the car seemed to drive fine with no reduced performance, aside from a slight shudder when I shut it off. I tried clearing the code, and then went out for a 20 minute drive. During this time the glow plug and CEL were off.

2) afterwards, I shut the car off, went to the store. When I came back, I turned on the ignition, and the glow plug light started flashing even before the car started. If I tried clearing it, it just came right back, even with the engine off. I drove home, again with no performance issues.

So, with that in mind, is it possible to determine if the fault lies with the TB unit itself, and if so, would this be covered under the emissions warranty? If it is I'll just let them deal with it. Also, after cleaning the "throttle body" is there an adaptation that needs to be done, like on a gas powered car?

I'm assuming it's ok to drive for the next few days, it doesn't seem to be acting up.
 
Last edited:

Bill1975

Active member
Joined
Jan 3, 2020
Location
Richardson, TX
TDI
2011 A3 CBEA
Ok, drove around for a while. No problems. Did shopping for an hour or so. When I came back the car would not start. It turned over and tried to start, but it sounded like the starter motor "missed" a couple times. Let it sit for a while. Finally cranked for about 10 seconds and it started. A bit rough, but it smoothed out and was fine for the 20 minute drive home. Scanned with VCDS, and there were no new codes aside from some preexisting electrical codes.

Given the hard start I'm a bit concerned. Appreciate any help!
 
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