DHenryTexas

Help!! getting a code for low coolant flow. Never had a leak. around 90,000 miles on the car. I am thinking it is a sensor. What do you think. Also where is the sensor located? By the water pump?

SMac770

You'd need to get the actual code, and rest of the DTC data if possible. Then you'd need to post up the actual engine code, four letters. I assume a '17 A4, even US, is using some EA888 Gen3 engine, if this is a 2.0T.

There's no sensor for coolant flow, thus the wonder of the specific P code or DTC code or whatever. It's probably some statistical code.

DHenryTexas

I am getting P00B7 code. I have the water pump and thermostat housing pulled. Do not see anything visually wrong. Do not want to spend $540 on thermostat and not fix low coolant flow issue. At least that is what code is indicating. Thoughts??

SMac770

What is the actual engine? What's the three letter code on the sticker on the upper timing cover? EPA says a 2017 A3 could be CNSB (1.8T 6-speed FWD), CNTC (2.0T 6-speed quattro), or CZRA (2.0T 7-speed FWD). Regardless, it appears all three are EA888 Gen3 (06K) engines.

https://forums.ross-tech.com/index.p...2/#post-244365
In that instance, it was a failed N422 not cutting off coolant flow to the heat exchanger before it should have been permitted. No idea how/why the guy randomly thought to try replacing that, there's no diagnostic path presented that pointed to looking at that device.

P00B7 is just a statistics computation, not any factual measurement. At least based on the code text.

But for the Gen3 evo engines, the code conditions imply it could be set by any number of errors managing the electrically operated thermostat. Rotary valve angle specified vs actual differs by more than 4°. You'd have to review the freeze frame data to see if that's the case. From the linked thread, we see he had (RVC = rotary valve control):Don't know if that RVC measurement deviation is a possible trigger condition for an original Gen3. Without clear documentation from Audi about how the P00B7 is computed, it's hard to speculate about a cause. The only things the system has outside of the management of the rotary valve is the cylinder head coolant temp sensor G62 and the post-radiator coolant temp sensor G83. So most likely the code comes from some kind of computation of expected change in coolant temp value based on the kg/hr consumption and the starting ambient temp. Which means anything anywhere in the system that causes coolant flow / coolant heating other than expected, or problems with the coolant temp sensors, would throw off that statistic.

DHenryTexas

Thanks for the reply. If I can figure out where the cylinder head temp G62 is located I’m changing it and one at radiator.

SMac770

G62 on the Gen3 should be on the back of the cylinder head. I've posted about it before, probably in a B9 A4/A5 forum here or at audizine.