Sunday, 27 October 2013

P0299 Fault Code on Audi A4 1.9 TDI BRB Engine

P0299 Fault Code on Audi A4 1.9 TDI BRB Engine  - Intro

Our Audi A4 1.9 TDI  suffered an obvious loss of boost and the engine light showing. I plugged in the OBD scanner and it flagged up a P0299 fault code described as "turbo booster under boost".

So armed with this code I went on various forums here and there to see what I could find out. However, I should have opened up the bonnet first, as the problem would have been immediatly obvious. THIS MAY HAVE ULTIMATLY BEEN DUE TO A WORN CAM SHAFT.

P0299 Fault Code on Audi A4 1.9 TDI BRB Engine  - Forums and Other Sources

1 - Apparently a common cuase for this code is a faulty pressure convertor valve.

"I would look at the Pressure Converter Valve (N75) located above the brake booster. It controls vacuum to the turbo. The part number is 1K0906627A. Here is a link to a picture of it . Hope that helps you out, mine was doing the same thing - no boost, no cruise control, and same code."

2 - The BRB engine has a variable geometry turbo, with bits that move inside, these moving bits are pulled / pushed by an actuator.

"Check your boost actuator with a vacuum pump from the autopart store. Autozone sells one that will be perfect for what you are testing. I guess I should do the test just to rule it out but I don't see how that could possibly be the problem given the fact that when it goes into "wimp mode" (that’s what I call it cuz it's not "Limp Mode") all I have to do is unplug the MAF sensor and Whaaalaaaa, got all my power back. The boost actuator is a mechanical device that I don’t believe can be fixed by unplugging the MAF. Please correct me if I’m wrong."

 3 - If the Actuator is the problem, then you will need to figure out which brand you have, actuators can only be sourced from specialist companies and not from your average parts place, they may require that you make a custom brcket for them to fit!

Borg/warner turbo rod extends with applied vacume.

Garret Turbo rod retracts with applied vacume.

Actuator type blck box = electronic – silver and round = mechanical.
P0299 Fault Code on Audi A4 1.9 TDI BRB Engine  - Actual Problem in my Case

There is an exhauist gas pipe that comes out of the EGR cooler, and upon opening the bonnet it was immediatly obvious that this had broken (stress fracture) and there was soot every where. The host gases had also melted a hole in the plastic engine cover.

It is unclear as to why this pipe has failed and one reason is :

"Good call Tom_B...EGR cooler was loose. The engine is doing some serious vibrating and some of the bolts had been damaged from the vibration so they replaced the mid and the rear bolts. I hadn't opened the hood with the engine running in a while and I was surprised by how much vibration was going on in there. I guess I got accustomed to it."

SO check that.

I found a loose bolt on the EGR cooler essembly, see below, so I teightened that and had the EGR pipe welded up by a local fabricator. I will post back in a few months and tell how things are going. There are other bolts that should be checked for tightness, but they are hard to get to.

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