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3 Posts
Discussion Starter · #1 ·
HELP!... 2002 JETTA TDI, about 143,000 miles. Bought it 6 months ago, runs great! Had timing belt and fuel filter replaced at that time. Occasional 17656 code initially, but nothing lately until a week ago on a long trip. I clear it, but it comes back after a couple trips. Even when the engine light is on, it still runs great, plenty of power, starts instantly, idles smoothly. Getting upper-40's fuel milage. Hard to believe there's anything really wrong, but what should I be looking at to get rid of the intermittant code?...

I've read thru some of the posts and it seems to be a code that is caused by problems with the injection pump, but most posts mention the engine running badly, so not sure that's the cause of my code!

Premium Member
23,902 Posts
Try this:
Possible Solutions

  • Check/Adjust Injection Start
  • Check Fuel Supply
  • Check/Replace Fuse(s)
  • Check/Repair Wiring/Connectors from/to Injection Valve (N108)
or this: http://www.myturbodiesel.com/forum/f9/free-eobd-ii-error-codes-software-2919/

Basically, it could be a wire shorting out quickly and throwing the code. Probably not a fuse since it's not constant. It's possible there is a fuel blockage in the fuel filter, (should be changed every 20,000 miles) or fuel tank, or that injection timing is off. Check the injection pump timing. There is a procedure on how to do this in the mk4 ALH engine timing belt article.

Premium Member
9,741 Posts
VAG Error Code: 17656

EOBD II Error Code: P1248

Fault Location:Start of injection - control difference

Possible Cause:
Loss of Power at high Engine Speeds.
Engine difficult to Start.

Start of Injection Timing Regulation not OK.
Injection Pump Control Range blocked/dirty (e.g. by Metal Particles).
Engine has stalled / ran out of Fuel recently.
Wiring/Connectors from/to Injection Valve (N108) faulty.
Injector needle lift sensor.
Fuel level low.
Pump timing.

Possible Solutions:
Check/Adjust Injection Start.
Check Fuel Supply.
Check/Replace Fuse(s).
Check/Repair Wiring/Connectors from/to Injection Valve (N108).

Special Notes:
Might by stored with other codes like 17654/P1246/004678.

Cheers chitty. ;)

2 Posts

Did you ever solve this issue? I am having the same problem. The code shows, I can clear it, but it pops back up again. The IP was replaced, but I have adjusted the timing folowing procedure, and it runs perfect right now. I put a new fuel filter in at the same time as the pump replacement. Anyone have thoughts on this?

If it was a fuse, which would I be checking??

Should I just clean the wiring connector with electronic cleaner??

Any help would be great...thank you!

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