Transmission Issue (P0740)

Hey all, I have a 2001 Jetta TDI with approximately 204,000 miles on it. Since around 190,000 miles I've had a P0740 (Transmission Clutch Circuit Malfunction). I've been coping with the problem by putting it in neutral whenever I coast to a stop. I want to finally tackle this problem and I was hoping you all could help.

I'm new here on the forums, but I've browsed here for the past month. I noticed CoolAirVW (I believe that was his name) posted a thread regarding this issue, and a fix or two that he had for people's issues. Since he made clear that there isn't any one fix for this problem, I decided to list my symptoms so maybe we could narrow down where the problem could be coming from.

My TDI has a Dr Jekyll / Mr Hyde type of personality regarding this issue.

• If the CEL is on, then my RPMs are higher than they should be at any given speed, and there isn't a rough idle or a clutch slip.
• If the CEL is off, the RPMs are normal for a given speed, but the gears shift early and I have a rough idle.

I read that someone mentioned that the first bullet point was a fail-safe system when the transmission isn't working properly. While I understand that, I DO NOT understand why it switches back and forth randomly. Driving over a pothole, or driving on a hot or cold day doesn't change it.

When I start my TDI, I need to let it idle for approximately 5 minutes in order to drive it at all. If I try to put it in reverse, or drive, then the car will sputter and then turn off.

ALSO, I forgot to mention earlier that my car has a P3130 code when the CEL is on. I don't know if those error codes are causing one another, or if they are completely unrelated.

If you all have anything that needs clarification, let me know. Thanks so much.

Your 1st bullet point is just failsafe for p0740 code. Once the computer sees the TCC slip it triggers the code and no longer tries appying the torque converter clutch.

Your 2nd "bullet point" doesnt make sense. I've driven a dozen cars or so that had P0740 and none of them had a rough idle. Maybe the rough idle stems from your P3130 EGR code. Maybe you should fix the EGR problem and then continue from there...

But...

There is no conclusive test to pinpoint the cause of P0740. Basically you have three choices.

1. Try a solennoid (I've never fixed P0740 with a solenoid but it is definatly possilbe)
2. Try valve body. This is where the problem usually lies.
3. Rebuild the trans. Make sure the valve body is rebuilt with the trans because this is where the problem usually lies.
EDIT: 4th option I thought of later
4. Try a torque converter (I've never fixed TCC code on a 01m with a converterbut it is definatly possible)

I have done over 100 01m valve bodies now, mostly for P0740 or TCC surging and have had nearly 100% success fixing p0740 and 100% success fixing the surging. The code and surging both stem from the same issue.

The valve body causes the 740 code because the pressure that should be going to apply the torque converter clutch "leaks" through the wear in the valves and "falls" into the pan, rather than applying the clutch. Problem is this pressure can also leak at other areas in the trans, like the stator, pump or the converter itself.

The diagnostic problem lies in that there is no way to measure this pressure, but even if you could all you would see is low pressure. You would have no way to pinpoint whether the leak in pressure was stemming from the valve body or from somewhere else.

DavidFoertsch said:

I read that someone mentioned that the first bullet point was a fail-safe system when the transmission isn't working properly. While I understand that, I DO NOT understand why it switches back and forth randomly.

Click to expand...

When the computer notices the TCC slip it triggers the code and stops commanding the TCC on. The high rpm comes when the computer stops commanding the TCC on. After "some period of time" driving the computer will start commanding the TCC on again, in hopes that the issue is resolved, and the high rpm wont start again till the computer notices the TCC slip again. It has to slip enough for the computer to notice and it has to slip frequently enough for the computer to consider it a "real fault".

DavidFoertsch said:

When I start my TDI, I need to let it idle for approximately 5 minutes in order to drive it at all. If I try to put it in reverse, or drive, then the car will sputter and then turn off..

Click to expand...

I didn't see this comment at first...

This might be related to the EGR code also, so maybe you should work at getting that fixed first.

But, sometimes a TCC solenoid will stick on and "Kill the engine". if this is what you got going on then you should try a replacing the TCC solenoid first. This is very easy to do.

see sticky solenoid example 2 in the following link.

http://forums.tdiclub.com/showthread.php?p=3592380

Awesome info, thanks a lot.

How would you go about changing the EGR valve?

DavidFoertsch said:

Awesome info, thanks a lot.
How would you go about changing the EGR valve?

Click to expand...

It's about a 30 minute job. Just unbolt it from the manifold, disconnect the vacuum line and put on a new one.

http://www.ebay.com/itm/99-00-01-02...TDI&hash=item2567e36b2b&vxp=mtr#ht_1865wt_988

So that piece would do the trick?

DavidFoertsch said:

http://www.ebay.com/itm/99-00-01-02...TDI&hash=item2567e36b2b&vxp=mtr#ht_1865wt_988
So that piece would do the trick?

Click to expand...

That looks like it came off a V6 gasser, not a TDI. Call or PM JasonTDI in Wisconsin for help here.

Hi, David,
there are probably a few hundred EGR assemblies available real cheap from the members of this club! Mine was working fine when I 'deleted' it...

Is there a "location" where people on here sell them?

i had exactly same issue with my 03 01M. Did not have rough idle or EGR code. Valve Body rebuild by CoolAir fixed it. I also had the pleasure of re-learning to check the fluid level with the car running.

sdeck said:

i had exactly same issue with my 03 01M. Did not have rough idle or EGR code. Valve Body rebuild by CoolAir fixed it. I also had the pleasure of re-learning to check the fluid level with the car running.

Click to expand...

Okay, then it makes sense that the rough idle/warm up issue I'm experiencing involves the EGR valve. I've seen some people that just needed to clean it, so I'll take a look at it before I buy the part.

David, while you are in there also look into the intake manifold and consider cleaning it if you see a lot of accumulation. Good luck.

I feel really uneducated about this, but truth is I am (I do have the correct tools for the job, however)! I'm having trouble FINDING the EGR valve on my 2001 Jetta TDI. Can someone give me a quick bullet-list to get to it? Thanks, I appreciate it.

I would suggest diagnosing or having someone diagnose why you have the EGR code. Changing the EGR valve wont necessarly fix it.

Agreed. However, the owner before me didn't do a whole lot of cleaning. I wouldn't doubt there being some major carbon buildup.

Also, it is still the original transmission at 204,000 (now with the TCC malfunction of course).

Do try cleaning first.
The EGR is the object bolted to the left side of the intake mani (with you facing the engine). It has 2 vacuum hoses connected, one for the EGR and one for the ASV, and an exhaust connection beneath.

Got it. I'll clean that out and post results once I've test driven it.

Well, I took off the EGR valve and pipe below and cleaned it all. I got really excited because it was VERY VERY dirty, and I thought that would be the fix to some of my problems. Unfortunately, that wasn't the case. I'm back to square one on the rough idle/warm up issue, and I'm guessing that the clutch solenoid will need to be replaced. Any other ideas/comments are welcome. Thanks.

After some more investigating, my car still has symptoms that lead me to believe (based on a bunch of "googling") that the warm up/rough idle/loud engine problem still has to do with the EGR valve. I might have a leak somewhere, I can maybe even here a small hiss near the valve or to the right of it, but I can't find a hose that's cracked. Any ideas?

Also, is there a test that I can put my EGR through to see if it's working properly?

Another observation!

I've noticed that the exhaust smell isn't "normal" for a TDI, I think. Could that mean that the EGR isn't working properly?

I don't know where you are in Wisconsin, but rather than guess at it, why not take it to JasonTDI's shop in Madison area? He is a resident expert here on TDI's and can save you some time (and maybe money).

I'm in Appleton, roughly 2 hours from Madison. I might give him a call first to see if he can give me any insight before I make the trip.

DavidFoertsch said:

I'm in Appleton, roughly 2 hours from Madison. I might give him a call first to see if he can give me any insight before I make the trip.

Click to expand...

Let us know how it turns out. You are lucky to have him available as he is one of the best with these TDIs.

After talking to Jason I did a couple of tests on my EGR. I unplugged the vacuum hose from the top and the car ran no different! Clearly something isn't right with the EGR, because the hose was sucking air like it should. Either the shutter or the piston is inoperable.

Similar Issue with P0740

I have been having similar issues with my 2000 Jetta TDI 01M. The car has 280k mi on it and has had P0740 from time to time but it is now not driveable in hot weather without the code and associated slip. It slips sometimes without the code but the 5 restarts usually clears. I have vag com and have tried to sort out the issues. The trans was rebuilt about a year ago by a reputable local trans shop - friend of a good friend with a car lot that does business there. Aside from some stripped bolts the work did seem to fix the major problem at the time - it tried to engage 2 gears at once when my girlfriend was driving and smoked it before she got in the drive way. I had purchased new torque converter and solenoids which were installed during rebuild. A new valve body was installed according to the shop (although now I am a bit suspect). Question now before I go back to the trans shop is that of measurement of pressure. Couldn't the pressure regulating solenoid give an indication of the pressure? In other words if the valve was fully closed (ie not by passing to get correct pressure) wouldn't that indicate that the pressure was not keeping up? I thought it was a control problem at first so I replaced the engine speed sensor (on the side of the engine behind the oil filter, the trans input sensor on the side of trans, and the sensor under the motor mount

More - The fan was bad too so both fans are now new - perhaps the fan was giving hot coolant to the trans cooler. Well the car must go back to the rebuild shop so hopefully it will still be on them.

David,

Please clarify. When you say you cleaned the "pipe" are you referring to the aluminum intake manifold or the rubber elbow. If the elbow, then clean the intake manifold. If you cleaned the manifold, you may need to clean the intake ports as well. Not difficult, but somewhat involved and a little nerve-wracking.

sdeck said:

David,

Please clarify. When you say you cleaned the "pipe" are you referring to the aluminum intake manifold or the rubber elbow. If the elbow, then clean the intake manifold. If you cleaned the manifold, you may need to clean the intake ports as well. Not difficult, but somewhat involved and a little nerve-wracking.

Click to expand...

The rubber elbow wasn't dirty at all, but I still scrubbed what I could. The metal pipe directly underneath the EGR itself was VERY clogged. I cleaned that out, and it didn't run any different.

I found a vacuum leak, so I replaced the hose and now I have more power and better braking. The rough idle and cold shut off are both still persistent.

I drove out to Madison and had Jason take a look at it. He said everything was running as it should, besides the transmission. He said that the call stalling out when cold, and the rough idle (in gear), are both transmission related.

That being said, I'm trying to find a solution to my transmission problem. I think I'd like to take the valve body off, clean what I can and replace the solenoids. I haven't done it before, so I'll need as much help as I can get.

cavemn2000 said:

...... Question now before I go back to the trans shop is that of measurement of pressure. Couldn't the pressure regulating solenoid give an indication of the pressure? In other words if the valve was fully closed (ie not by passing to get correct pressure) wouldn't that indicate that the pressure was not keeping up?

Click to expand...

The only pressure you can measure is line pressure. There are dozens of pressures inside the transmission and you can only test line pressure.

Just some quick pressure off the top of my head.

1. solenoid feed pressure
2. k1 pressure
3. k2 pressure
4. B1 pressure
5. B2 pressure
6. converter charge pressure
7. converter release pressure
8. Boost regulator valve pressure
9. ect, ect, ect

You have a incomplete understanding and your question is impossible to answer. Assuming you have P0740 code you must understand that testing line pressure isn't showing you much of anything regarding Torque converter charge pressure or Torque converter release pressure. As with most pressures these pressures are just plain impossible to test in anyway shape or form that a layperson or even most transmision shops can do.