Doctor786

4 hours ago, jdragon said:

You're welcome. Sounds like everything is OK now then.

Sorry if you misunderstood me, problem is still there.  I still have engine management light on however no restart warning after 650 miles keep disappearing and than coming back. 

4 hours ago, jdragon said:

This link might yield something useful, especially checking connectors.

https://pmmonline.co.uk/technical/resolving-an-audi-a4s-adblue-warning-fault/

I don't know about the heater reference 'A'. I've checked the A5 B9 erWIN manual and the only reference I can find to a heater is in the supply line for the V437 pump.

Might be helpful to post the full scan, if you have it.

I don't have full scan mate, 650 miles warning disappeared yesterday but came back again today. At least it reset back to 650 miles again. Car runs fine with out any issues and still doing dpf regens as normal.

No I didn't because I only filled it week ago so I knew there was plenty of adblue in the tank. This time I have put 5 liters of adblue just to to be sure without any luck. However after putting 5 liters of adblue warning did disappear for 3 days before it came back. Is there any way to find out which one is heater A?. Thanks for the quick reply mate.

I had this message 4 months ago as well but simple turn off the engine and restart again solved the issues but the same issues has come back last week but this time with engine management light as well. It started the countdown to 650 miles and when it got to 550 miles some how it disappeared but came back after I did almost 300 miles. So countdown is down to 600 miles again at the moment. I am getting 2 error codes.

P20BC : Reductant heater "A" control circuit high

P20E8 : Reductant pressure Too low.

Any ideas which heater is "A"? is it the one inside the adblue tank where I have to replace whole tank along side the heater or is it the one outside the tank connected to hose pipes and can be changed on its own. Any help will be much appreciated in advance. As a taxi driver I will be doing remaining 600 miles in just 3 days so need to get it fixed as soon as possible.