m1964

Hi,

A coupe of weeks ago my wife called and said, "There is a light on the dashboard something to do with engine repair."
I had the Q scanned at a local AutoZone (5 min. from the house) and their computer detected "unexpected low voltage on the secondary air injection system pressure sensor circuit".
I booked an appointment at the dealer thinking that code indicated the "famous" carbon build-up problem on 3.2L motors, which would be covered by Audi up to 120K miles/10 years. Our Q5 has only 63K miles.

The SA called me today and said they diagnosed "problem with the sensor circuitry" and they want to replace the pressure sensor that monitors air pressure in the secondary air injection system, at the cost of over $600.
According to SA, if that would not fix the problem, they will proceed with cleaning the air injector ports, which will be covered by Audi.

I said to him that, IMO, the sensor is a part of the same secondary injection system and most likely has carbon build-up as well and should be covered by the same TSB that covers air ports cleaning. The SA replied, "The TSB does not cover the sensor, only cleaning of the ports".

I called Audi of NA and explained them the situation- the representative replied, "I will pass this information to an appropriate person and we will review it".

I live in a state that conforms to California warranty- in California, the emission control system is covered to 70K miles/7 years.

I wonder if the secondary air injection system is a part of the emission control - if it is, the replacement of the air pressure sensor most likely would be covered by the California warranty then.

Can anyone tell me if the secondary air injection system is a part of emission control?
What exactly the secondary air injection system does to the car?

Thanks a lot

Bob Petruska

I would say that the secondary air injection system is part of the emission system.

That sensor goes for about $100, or less, and is very easy to replace. It's at the top/back of the engine. I would change it myself, or have a local garage change it for a lot less than $600. If that fixes the issue, then you won. If not, then you are sort of stuck as the Audi dealer will now say you side stepped them, and you want a free clean. The dealer was going to make about $400 on the sensor replacement.



Secondary Air Injection System

The secondary air injection system improves the secondary oxidation within the catalytic converter which are due to the rich mixture during the cold start phase where the exhaust emissions contain an increased level of unburned hydrocarbons, thereby reducing harmful emissions. The heat released by secondary oxidation shortens the startup time of the catalytic converter considerably, as well as significantly improves emissions quality during the cold-running phase.

- During a cold start, the secondary air injection system injects air behind the exhaust valves. This produces an oxygen rich exhaust gas, causes the after burning and reduces the heating-up phase of the catalytic converter.

- In addition, the secondary air injection system is switched on (after a delay) during idle after every subsequent engine start (up to a maximum coolant temperature) and is checked through on board diagnostic functions.

For all secondary air injection system component locations, removal/installation procedures and torque specifications, refer to the service manual.

m1964

Hi Bob,

Thanks a lot for a quick reply- my Q5 would be covered by California warranty if the SAI system is considered a part of emission control system.
I did have a feeling that the sensor is not too difficult to replace, but did not want to do it w/o knowing where to look. Also, I understand that the CE code needs to be cleared after the sensor change.

is there any way you can post a diagram or a picture of the area where it is located?

Thanks a lot

Redd

Hmmm...The sole purpose of the secondary air injection system is to enable the optimum operation of the catalytic converter, and the sole purpose of the catalytic converter (unless you grill lunch on it) is to control the emissions.

I'd be tempted to phrase it just that way to the non-technical person answering the phones at AoA, and ask them if you need to have the California Air Resources Board (CARB) confirm that with them directly, or if there is another regulatory agency they'd prefer you to tell that AoA is violating state laws.

Shouldn't take them more than 24 hours to "review" that and authorize your service. If it does...file complaints, it will help out other owners with similar issues.

"Papa Spank".

Bob Petruska

This should help.............

m1964

Bob,

Thanks A LOT

m1964

Hi Redd,

thanks a lot for reply-I like your very clear explanation of the function of the SAI system.
I did speak to TWO SAs at the dealership- one yesterday, and one (who "takes care" of my Q5) today- both adamantly denied that the SAI system and the pressure sensor is a part of the emission control system.
I asked, "Is the SAI system a part of the emission controls", and the reply was "Absolutely not" from both SAs. The second one said this: "Even it has to do with emission controls it is not part of it"...
Now, thanks to your post, I have a good idea what I am going to say to a representative tomorrow.

atc98092

The problem with the emissions warranty is that it lists specific components, and if it's not listed it's not covered. That's why VW was not covering the failure of the AdBlue tank heater. Obviously, AdBlue only exists to control emissions, but the EPA approved document didn't list it.

Now with the TDI settlement VW has to pay for virtually the entire powertrain, from the fuel tank, pumps, injectors, cat converters, AdBlue systems, etc.

m1964

I finally changed the sensor today- first, I tried to erase the code (using a little $49 gismo from Amazon), but the code would come back immediately.
I was able to find the sensor by tracing the "pipes" from vacuum valves to the middle where there is a "box" containing the air injection pressure valve which is located at almost 90 degree angle to the engine (almost vertical).
After I felt the sensor by hand, I was able to see a small part of it through the wires and hoses on top of it.
I did break one of the four tabs holding it in, but I think that 3 remaining tabs will keep it in place just fine since there is no pressure on the sensor.
I may try, at some point, to place a zip tie around the sensor and the box it is in to keep the two together.
To my surprise, the sensor I pulled out was not an Audi sensor but VDO/Siemens part:



new OEM sensor on the left



Old sensor on the right

After I finished installation, I erased the code and it had not come back...yet.

I hope that it was the end of the problem and the car does not have any significant CB.

Thanks to everyone who replied to me for your help and support.

ianchot74

Hi. I have P2432 on my wifes q5 2010 3.2. please let me know if the sensor fixed the problem. Also i spent over an hour till i founnd ( felt) the sensor and felt 4 tabs but couldnt figure out how to to take it out and also how to disconnect the wire. any advice will be appreciate it. thanks