My 2004 Diesel Opel / Vauxhaull Zafira A had carbon buildup somewhere in the engine and/or in the exhaust system. It did not pass emission test. The mechanic advised me to drive the car on the highway up to 5000 RPM to push the buildup carbon out.

I was very eager to try it out the next morning. It was perhaps -8 celsius (46 fahrenheit). I started the car cold and put it to neutral. After idling one minute or so, I pushed the gas pedal to let the engine run at between 3000 and 5000 RPM.

A couple of minutes later, a yellow "Service Vehicle Soon" light came up. In Opel / Vauxhall's language, it does not mean the car needs service, but rather something is faulty.

I stopped the car, realizing maybe it was a bad idea to let the engine run at such high RPM at a cold start on a cold morning. However, there was quite some black carbon that came out of the exhaust pipe that were left on the ground.

The yellow "Service Vehicle Soon" light became on and off since then. Three days later, now it is almost always on. The car loses its power when the light became on. However, the light goes away after the car ides for a while.

I don't have an OBD reader at the moment. I don't know what the actual error codes are.

Today I changed the air filter and added coolant. The box that hosts air filter is not seen in the photo below, but it is on the top left under the hood: enter image description here

The picture below has a better view. The box to the left hosts the air filter. To the right you can see some oil like stain. Here I suspect that there may be a leak: enter image description here

The photo below is a closer look: enter image description here

This photo has an even better view of the potential issue: enter image description here

Here is a short video: https://www.youtube.com/watch?v=Q3OlXoEn2Wg. You can see that the hose is a bit loose. Is this intended?

It seems to me that there is a leakage of something here. Do you think that there is a leakage? What is leaking here? What are the names of the components, both the smaller hose and the thing that the hose goes into, where between the hose and the hole there seems to be a leakage?

I remember seeing the oil stain before I changed air filter. However, I did not look closely at the time. Is it possible that the leakage was caused by me yanking the hose that goes out of the air filter box?

Do you think this may be causing the problem? I'm asking because on this car model, it is also very common to have a broken turbo intercoolant pipe, which from Youtube videos seem to be located elsewhere. So there is a possibility that the shown potential leakage in the photos and video are insignificant that there may be a problem elsewhere, such as turbo intercoolant pipe.

  • When the mechanic said « drive the car on the highway at 5000rpm » why did you think that revving the engine when stationary on the drive was equivalent?
    – Solar Mike
    Commented Dec 7, 2021 at 20:03
  • I was impatient. I wanted to try the trick out right away. It was a mistake. Commented Dec 7, 2021 at 20:15


You must log in to answer this question.

Browse other questions tagged .