2003 Golf TDI Limp Mode-Codes P0321 & P0725

2003 Golf TDI
Automatic Transmission (flushed trans at 100K)
136K miles

Driving on the freeway, my engine died. After a few minutes, it restarted and I was able to drive it home (5 miles). I can't remember if it was in Limp Mode or driving normally. I was worried about getting home as the dash had Check Engine Light and Glow Plug light flashing.

At home, it only ran in Limp Mode. It showed codes
P0321 Powertrain Ignition/Distributor Engine Speed Input Circuit Range/Performance.
& P0725 Powertrain Engine Speed Input Circuit
I replaced the engine crankcase sensor and the transmission output sensor (the one under the driver engine mount). All fuses are good. Glow plug light went out, but the CEL was still on. It only runs in Limp Mode. Disconnected battery for an hour. Reconnected and the same codes showed. Tachometer and speedometer work fine.

A mechanic had it for 8 days and said the sensors kept confusing his mechanic. He said it might be the Transmission Input Speed Sensor. I took it back home since they did no work to it.

I read about unplugging the MAF and checking for any change...there was no change. I can get around town (up to 45mph without any problem), as long as I manually shift from first to 3rd (still can't get 4th gear).

AAMCO Transmissions suggested that my sensors are bad since I got them from an auto parts store versus the VW Dealer. He also said "We don't work on VW diesels". I considered changing both sensors (again) and the Transmission Input sensor (towards the back of trans).

I've been pouring over all the other bulletin boards and can't seem to find an answer. Any other suggestions?
I've come down with the flu, so, I hope to get back to this car in a couple weeks.

Thanks to everyone for your thoughts and suggestions.

P0321: http://wiki.ross-tech.com/wiki/index.php/16705/P0321/000801
(likely the crank position sensor - CPS)

P0725 code (likely a byproduct of a flaky CPS):
http://forums.tdiclub.com/showthread.php?t=393949

I'd at least check wiring to the CPS, perhaps drop in a new CPS.

IIRC, the P0725 is one of the DTC's I had when the above mentioned CPS started acting up. The attached cable must have had broken wires from all the heat. I changed it just a few weeks ago and no more hard starts and stalling.

Thank you very much for your help.

As soon as I can, I'll swap the Engine Crank Position Sensor (VW brand only) and the Engine Camshaft Sensor and cable. I think I might also swap the Transmission Output Sensor (G68) with an original VW part and the Trans Input Sensor (I think it's G28). Time to end these sensor problems.

If I have additional problems, I'll update you. Thanks again.

Look over on kansascitytdi.com for some things specific to the transmission. User CoolAirVW (KCTDI) can be helpful.
Hard to believe AAMCO wouldn't take your money.

Regarding AAMCO, that's how I felt, especially when they were the ones who did a complete transmission flush when I bought my 2003 Golf in 2014. They gave me 2 names they refer to for diesel engines.

I think I was confused with the CPS. I thought UhOh referred to code P0725 as Camshaft Position Sensor (instead of Crankshaft Position Sensor). At this time, I'm not going to worry about the camshaft sensor, especially since I can't seem to locate it. I think this is only for cars newer than mine.

Thanks again for everyone's help.

There is no CMP sensor on the ALH engine, only the CKP sensor (G28 engine speed sensor).

The Engine controller (ECU) sends THAT data across the CAN bus to the Transmission controller (TCM). If that value is lost to the ECU, the TCM will also set a DTC.

If you are using a generic scan tool, you may find both lumped in the generic place of the ECU, but a proper scan tool will have each of them found in their proper place.

I feel like a post this five times a day, but generic OBD2 scan tools suck. They will send you on wild goose chases, and not provide you with the proper data or means to get at the proper data for a proper diagnosis. I really wish people would just do themselves a favor and stop using them.

You should be happy AAMCO sent you off. Interweb guessing this car needs further and correct diagnosis. Take your time, seek out best sources for information.

I knew about the communication between the crankshaft sensor and the TCU, and after changing this sensor I can feel the difference in up and down shifting; the 09A is more responsive. The attached cable apparently had one or more bad faulty/cracked wires due to age.

I changed the crankshaft position sensor. I decided to also change the aging vacuum lines. I still have a CEL and the car is still in limp mode.

I'm going to try "oilhammer's" advice. I'll drive it to the auto parts store and let them scan fof codes. My son used his scanner and it's a generic unit. I'll mention the problems to him.

Guess I'll do more reading on the potential cause and hope someone can help steer me in the right direction.

Thanks again, everyone.

The "parts store" is just going to use a generic scan tool as well. They'll like to sell you a bunch of parts you don't need though! And the goose chase continues.....

OceanHorse said:

I changed the crankshaft position sensor. I decided to also change the aging vacuum lines. I still have a CEL and the car is still in limp mode.

I'm going to try "oilhammer's" advice. I'll drive it to the auto parts store and let them scan fof codes. My son used his scanner and it's a generic unit. I'll mention the problems to him.

Guess I'll do more reading on the potential cause and hope someone can help steer me in the right direction.

Thanks again, everyone.

Click to expand...

You could try finding someone with VCDS, though I know they're a bit light in California. Also try any local VW enthusiasts clubs or groups, the gas cars use the same diagnostic tool.
Good call on following OH's advice, he's a 99%er. I might look close at the wire connects, especially between the TCU and ECU.

As Oilhammer says, the goose chase continues. I just checked the actuator and vacuum like with a Mityvac and it’s working fine.

Someone suggested that what I have isn’t an engine problem, but rather a trans issue. Putting the auto trans in Drive, I’m always in 3rd gear and it never down shifts or up shifts. Ivan manually shift from 1st to 3rd. If I shift to Drive, I’m still in 3rd gear. The thought was that my trans doesn’t know what gear it’s in.

I have no idea how to test a trans outside of swapping input and output sensors. Like I mentioned earlier, AAMCO told me they don’t work on diesels.

Any thoughts on the transmission?

Aamco is a place for idiots. All Automatics Must Come Out. I love the "we don't work on diesels".... they say that of course because they have no idea the 01M bolted to the ALH is the same 01M bolted to the gasoline 4 cylinders.

Again, without a proper scan tool, guessing is all you've got. May as well get a dart board.

Get it to someone who can properly look at your car with the correct equipment. It is a VERY simple system, for both the engine and the transmission. The ALH has, bar none, THE simplest engine management system of ANY car or truck sold in this country in the last 25 years. And the transmission is not much different than any other electronic controlled automatic sold here.

I'll do that.
Thanks for the advice and comments.

Problem solved. Driving to the 5th mechanic’s shop (import trans specialist), engine light went out. Instead of manually shifting from 1st to 3rd gear, I put it in Drive and it ran perfectly. The mechanic hooked up his instrument and showed code P0725 was gone. BTW, none of the 5 shops had a Vag Com (what’s gives in SoCal?).

As a footnote, the night before, I saw a tiny water puddle (recently rained) next to the trans cooler. I dried it and wiped small drippings of oil. Maybe this helped. Who knows?

Solved is good!
These TDIs were not sold new in California, part of the reason you're lite on shops. But the VCDS is a tool for all VW, Audi, etc. so somebody should have one.