BEWARE ALL S4(B5) AND RS4(B5) OWNERS

[Turbo Joe]

Recently one of the Exhaust Gas Temperature Sensors went on my S4 twin turbo(B5). Recently the wanker technics at Audi have modified this part and not informed anybody about the change.Ref new part number to old part number.
078919529D-Original part for S4 and RS4.
078919529F-New Modified Part.
As we can see the prefix 'D' has been changed to an 'F' but thats isnt all that has changed. This new prefix 'F' part is less tolerant to high temperatures than the old and a limiter programmed into the sensor reduces performance by 10-15%.Ie modified S4-330bhp, down to 300bhp and standard RS4-380bhp down to 342-345bhp and trust me you can feel the difference from the original part. If you can hunt down the old part, my advice is do that unless the power drop doesn't really bother you.

[SimonS4MTM]

How did you find this out?

[PhilT]

How did you find this out?

I'd be interested too.... Seems like a bold first post to me.

[Dippy]

Normally a temperature sensor does just that, so it would be more than just a sensor in order to have a "limiter built in". After all this is a simple thing for the ECU to do so why rely on the sensor?

Morpheus, can you shed any light???

[SimonS4MTM]

Dippy, that depends if the sensor is a silicone chip or a RTD. If it is a solicone chip type sensor (though unlikely due to the temps) they often shut off if the temperature goes above the normal operating temperature of the sensor to prevent internal damage.

[Turbo Joe]

What was happening was people were blowing their turbos and claiming replacements and repairs under warranty so this is audi's sneaky backdoor protection plan to cover their backsides. Extensive research was conducted,to the point where I tried to find out who made the sensor.I think it is in house made cos I checked with Bosch,Hella,Valeo and Seimens and none of them seemed to have heard of the part or have it under record. I also know of a gentleman with an RS4 in Turkey and he experienced the same problems. He eventually found the part in the deepest ,darkest part of Germany,a name he hadn't even heard of and they had 2 left.I emailed Audi UK to ask them what they are playing at,if the part isnt made in house,who makes it and why werent people informed of the changes. I am still awaiting a reply and I will keep you guys informed on developments. In the meantime, if that part goes defective on your car, be prepared for a reduction in power and torque with the replacement. Sorry to be the bearer of bad news but somebody has to spread the word if Audi won't!

[Turbo Joe]

I also found that this sensor has been programmed differently with a much lower tolerance level to normal operating temperatures, let alone high ones. One gear you can feel your reduced performance and the next you can feel a futher reduction.This is a real bummer.How am I supposed to eat Porsches for lunch and shake M3's?

[simple1]

Had mine replaced recently by Audi, and dont notice any change in performance, infact it made me realise how long I had been driving the car with reduced performance.........so not too sure what the story is.

[zorroRs4]

keep us informed mate,cause am about to change them.
is true that S4 and Rs4 use the same Exhaust Gas Temperature Sensors with the parte number above?
any one know the price for each?
thanks

[Turbo Joe]

Part number for the S4 and the RS4 are exactly the same except the original part number ending in the prefix 'D' was specifically reserved for the S4 and RS4 only due to their high performance. The new part number end with the prefix 'F' unfortunately us S4 and RS4 users will have to share with the A6 2.7T the All Road Quattro and a few other stragglers in the Audi range. Unfortunately many people will read this and because their exhaust temperature sensors are fine AT THE MOMENT,won't really take any notice of this( you know the "Well it hasnt happened to my car so I don't need to worry and good luck to those it has happened to ,ha ,ha).I personally think that a few heavy emails in Audi's direction will at least get them to look at the calamity they have put S and RS users in just to save money and at least get them to address the issue because it will be an issue for a good number of you if it hasnt already been one day.Ah yes prices.

Original part-078919529D= £219 in UK(Price was £90 when bought in Germany)
New replacement part-078919529F= £158 in UK(150 Euros in Germany- £104)

[Turbo Joe]

By the way I went hunting all over the world for mine. I must have picked up at least 15 languages by now. Finally landed one in the states for about £180.Sending it over Fed Ex Express. We shouldnt really have to go through this kefuffle just to retain the same performance standard.Technically they could be in big doo doo because the car is now not performing to the specs it was at when you bought it and what it was advertised to do.Email em and put the pressure on people.

[sitas3]

could it just be that your newly fitted sensor is faulty?

[Turbo Joe]

could it just be that your newly fitted sensor is faulty?

Nope,got a 5051 check at two places and no faults were found after the replacment sensor was installed. That was my 1st thought when I noticed the reduction of power but that was wishful thinking and too easy. Its taken me about a month to investigate it but I can confirm that this is the truth and sorry to say, you will notice it too when your sensors go.My advice, email Audi and ask why they havent disclosed this information cos as far as I am concerned, this is one of the lowest deeds in the book just to save on money and materials(i.e turbos) and they need to be held accountable for their actions.

[simple1]

you must be having a laugh........... Audi UK dont do accountable look at the wheel issue some of the original owners had, and they had the motoring press on their side..........

[Jani]

Did you have your Motronic reseted to defaults? The sensor thing sounds too weird, they can't lower specs at this stage I'd say. Hopefully.

Had mine replaced 2 months ago, no loss of power, just the opposite.