Eddie1337

Hey guys, hope you are doing well.
As of 1 year now I am an owner of an Audi A6 3.0L TDI C7 and so far so good.
I have done proper maintenance of the car, changed the fly wheel, new brake pads and rotors, change oil regularly etc.
Lately I am having an issue when shifting 5th gear to 6th.
If I drive normally even at high speeds everything is fine but when I hit the gas pedal hard like almost flor it the gears change all fine except 5-6 gear which I will feel like a light shake of the car like left and right thingy.
So this basically only happens when hitting the gas pedal hard and it only happens with the 5-6 gear, it is very odd. I am also starting to get a code on my obd code reader P072600 Engine Speed Inp. Circ.
I have done some google search but I am not quite sure what it is yet. I went into a transmission service shop and they said the transmission looks good to them but they did not check the code reader.
Has any of you ever had this issue before?
How can I tackle this issue further?
I really do not know what to do, I would not want to drop the gearbox and open it up as it will be very expensive probably around 2k euros.

Thanks in advance!

superswiss

P0726 can have multiple causes, but the gist of it is that it's getting incorrect, irrational or erratic engine speed readings, which will lead to the transmission shifting erratically. A quick search brings up the following list as potential causes:

• A failed engine input speed sensor
• A failed transmission output speed sensor
• A short or open in the wiring harness to one of the sensors
• A loose connection to one of the sensors
• A faulty crankshaft position sensor
• A faulty shift solenoid
• Dirty, contaminated or low transmission fluid
• Faulty PCM (rare)

PEB60

Have you had the Transmission serviced or changed the fluids in your differentials?
If you do a transmission filter/fluid flush/fill (which takes about 9L of fluid assuming that you are driving a car with the ZF 8 transmission) and then do a proper reset of the adaptations and re-learning, you might find that your problem goes away.
If you have already done this service then I bump to the next forum member!
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Eddie1337

Since this is happening only when hitting the gas pedal hard and only in 5-6 gear I am leaning more towards a faulty solenoid but I might be wrong.
I will go to the transmission shop shortly and see what they say to me.

Eddie1337

No I have not done any fluid change on the transmission or the differentials.
I will have to change my engine oil etc very soon. I might do that as well but I will talk to the transmission shop first and see what they have to say.

Eddie1337

Hi all,
I have been to the transmission shop twice by now but he keeps saying this is not related to the transmission itself or any sensor with the gearbox and insists that I should go to electro auto shop instead if they may find the issue.
I went to another transmission shop and without checking or anything he wants to bill me for a full rebuild. I am not doing that.