TDI Power Loss: Common Causes & Solutions

Hi everyone,

Something is 'acting up' with the engine in my Audi A4 TDI, engine code AFN. Here's what's happening: During normal driving, the power suddenly cuts out around '2500-3000' RPM. I turn the ignition off and on, and everything is okay again until it happens again. The error memory doesn't show anything, and the workshops want to replace all sorts of things. I've heard that many TDI engines have the same problem. Does anyone have any other suggestions for me?

Best regards,
Holger

Hello,

Please use the search function first. There's a lot of information available on this topic.

Hello,

Your problem sounds like a typical issue related to the turbocharger's boost pressure control.
Have the engine management error codes read by another workshop immediately after the error appears. Those guys tend to just clear errors they don't understand...
Possibly, the diagnostic device was also used incorrectly, for example, by first clearing the error memory and then reading it.

Best regards, Rainer.

Do you experience significant black smoke within a certain RPM range? If so, please inspect the transition pieces connecting the pipes to and from the turbocharger.

Hello Holger,

I had the same problem with my Passat. It annoyed me for a long time. In my case, the cause was the turbocharger pressure control valve. That's the part where the three vacuum hoses are connected.
Maybe this will help you.

Best regards, Franz.

Thanks for the information! About how much does that part cost? I might need to replace it sometime. Best regards, Holger.

Hi.

The boost pressure control valve costs approximately... (I'm not entirely sure of the exact price).
107 euros. Not cheap. I would first try to get one to test. Check the hoses or the VTG adjustment before you replace the valve.

Hello Holger,

The LDM valve costs approximately 30 euros. The investment has definitely paid off for me. I also received a tip from a forum member who had the same problem with an Audi A3.

Good luck, Best regards, Franz.

Hello everyone! I took the valve out today, and something seems to be 'moving' inside it when you shake it. That's strange, isn't it?
Best regards,
Holger

Hello Holger,

I think an exchange would be worthwhile.

Best regards, Franz.

Hello, this part costs approximately 110 euros from Audi, excluding installation. Other forum members also reported the same price.
Best regards,
Holger

Hm, somehow I have the feeling that you are talking about 2 different things.

Franz is referring to the 'boost pressure control solenoid valve.' It's a small box that you can easily replace just in case. It costs around 25 euros.

And finally, 'atzleh' probably refers to the entire pressure vessel! Because the price of around €110 seems about right for that.

'Mist! I meant the turbocharger boost control solenoid valve, part number 1HO 906 627 A, original from an Audi workshop, costing €110.78. It has 3 ports and a voltage connection!'

Hello Holger,

It's really strange. I replaced the turbocharger boost control valve in my Passat six months ago, and it cost exactly 30 euros, as I mentioned before. I believe your valve is the same. Mine is attached with two screws, has three hoses, and one electrical connector (2-pin). Please check the price again.

Best regards, Franz.

Hello fellow DIY enthusiasts,

"So, the boost pressure control valve for my 1Z also cost around 30 euros. The one for various other TDIs is supposed to cost 110 euros. It looks a bit more robust, and otherwise it doesn't seem much different. There are apparently different solenoid valves with significantly different prices (depending on who calculated it)."
Unfortunately, I cannot say whether the two valves differ in function.

Different solenoid valves were installed for the various engines. In my ALH engine, there are two different types alone.
One that starts with a part number beginning with 1H0...
the other one is 1J0...
Both are installed in the Golf IV with the ALH engine, using the 1H0... part number, but only up to a certain point in model year X (which should be 1999), after which the 1J0 part number was used.
The 1H0 part costs approximately 110 euros, while the other one only costs 30 euros.

Unfortunately, I have the more expensive model. I would like to know what the difference is between the two - both operate with negative pressure. Could it possibly be due to the cross-sectional area?
It would be interesting to know which other parts were modified (e.g., turbocharger wastegate, engine control unit, etc.) - does anyone know more?