I'm seeking some expert advice regarding a recurring fault code that has been popping up on my 2016 Audi A6 Avant 2.0tdi. The code in question is 9658 - Reductant Pressure Sensor Circuit, P204B Implausible Signal.

The check engine light has appeared twice in the past two weeks but disappears after a couple of heat cycles. Has anyone else experienced this intermittent behavior with the same fault code? I'm curious to know if there are any insights or potential explanations for this pattern.

In addition, last week I encountered an AdBlue system fault (No restart in 600 miles). It disappeared after restarting the vehicle. It's worth mentioning that when I scanned the car using VCDS, no other faults were displayed (except the above-mentioned). Could there be any connection between the AdBlue system fault and the Reductant Pressure Sensor Circuit fault code?

I'm eager to hear from those who have successfully resolved these issues or have encountered similar situations. Your knowledge and suggestions for troubleshooting steps would be greatly appreciated.

So far searches in google suggest replacing the AdBlue pump, but the symptoms and the fault code are not quite the same.

Thankfully, I have not experienced any noticeable performance issues with my Audi A6 so far, but I'm concerned about any potential long-term risks associated with these fault codes.

Thank you all in advance for your invaluable insights and expertise!

 

 

8 hours ago, H11KUC said:

I'm seeking some expert advice regarding a recurring fault code that has been popping up on my 2016 Audi A6 Avant 2.0tdi. The code in question is 9658 - Reductant Pressure Sensor Circuit, P204B Implausible Signal.

The check engine light has appeared twice in the past two weeks but disappears after a couple of heat cycles. Has anyone else experienced this intermittent behavior with the same fault code? I'm curious to know if there are any insights or potential explanations for this pattern.

In addition, last week I encountered an AdBlue system fault (No restart in 600 miles). It disappeared after restarting the vehicle. It's worth mentioning that when I scanned the car using VCDS, no other faults were displayed (except the above-mentioned). Could there be any connection between the AdBlue system fault and the Reductant Pressure Sensor Circuit fault code?

I'm eager to hear from those who have successfully resolved these issues or have encountered similar situations. Your knowledge and suggestions for troubleshooting steps would be greatly appreciated.

So far searches in google suggest replacing the AdBlue pump, but the symptoms and the fault code are not quite the same.

Thankfully, I have not experienced any noticeable performance issues with my Audi A6 so far, but I'm concerned about any potential long-term risks associated with these fault codes.

Thank you all in advance for your invaluable insights and expertise!

 

 

Hi its probably a fault in the wiring loom from the tank which is fairly easy to replace.

Steve.

Thank you Steve, I'll check it out this weekend.

On 5/16/2023 at 11:40 AM, H11KUC said:

I'm seeking some expert advice regarding a recurring fault code that has been popping up on my 2016 Audi A6 Avant 2.0tdi. The code in question is 9658 - Reductant Pressure Sensor Circuit, P204B Implausible Signal.

The check engine light has appeared twice in the past two weeks but disappears after a couple of heat cycles. Has anyone else experienced this intermittent behavior with the same fault code? I'm curious to know if there are any insights or potential explanations for this pattern.

In addition, last week I encountered an AdBlue system fault (No restart in 600 miles). It disappeared after restarting the vehicle. It's worth mentioning that when I scanned the car using VCDS, no other faults were displayed (except the above-mentioned). Could there be any connection between the AdBlue system fault and the Reductant Pressure Sensor Circuit fault code?

I'm eager to hear from those who have successfully resolved these issues or have encountered similar situations. Your knowledge and suggestions for troubleshooting steps would be greatly appreciated.

So far searches in google suggest replacing the AdBlue pump, but the symptoms and the fault code are not quite the same.

Thankfully, I have not experienced any noticeable performance issues with my Audi A6 so far, but I'm concerned about any potential long-term risks associated with these fault codes.

Thank you all in advance for your invaluable insights and expertise!

 

 

Hi did you solve this problem I seem to have the same symptoms thanks 

Hello,

Unfortunately, I didn't. It took me many hours of browsing forums and engaging in further discussions with the garages before I decided to map out the unit.

Since I've conducted some research, may I advise you to consider the following: Check and clean the Adblue connections. Follow the pipes from the Adblue tank to the engine and see if you can identify any frost-like abrasions. If yes, replace the pipes. Also, try going for an extended ride; sometimes the nozzle can become blocked, and if you drive for a longer duration, it may clear the blockage. Lastly, if none of the above helps (this was my case), you should typically replace the Adblue pump as the sensor is integrated with the pump and cannot be replaced separately (expensive). I hope you'll find a straightforward solution. Oh, forgot to mention that you need to top up the Adblue. If your level is low, this can sometimes trigger the same error. Good luck.