P261A – Coolant Pump 2 issue (pump failure), need advice.

[jkeeeng]

Hey guys!

I am driving Audi A4 B8 2.0 TDI 170 with CAHA engine.
Have a following problem with auxiliary coolant pump.

4875 - Coolant Pump 2
P261A 00 [175] - Open Circuit
MIL ON - Confirmed - Tested Since Memory Clear
Freeze Frame:
Fault Status: 00000001
Fault Priority: 2
Fault Frequency: 2
Mileage: 224221 km
Date: 2016.05.06
Time: 07:40:02

From freeze frame I can say it happened in the morning me driving to work, but check engine sign appeared only in the afternoon same day, when I started warmed engine. I tried to clear the fault code, but with no success. After few tries check engine sign disappeared, but the fault code is still there.

Pump makes no sound. Found pump pinout on one of the forums. Pin 1 and Pin2 (motor) and pin 3 signal to ECU. Checked pump resistance, it seems no connection at all. So I assume the pump is dead. I decided to order coolant pump today, and unfortunately no one keeps it in stock and it will arrive only on Tuesday afternoon. At Audi dealer they quoted me 145£ inc. VAT, so not so bad. Pump part number is: 03L 965 561 (maybe someone will find it useful).

I will try to replace it myself, as from other people experience it seems not difficult.

Got the following few questions to you guys:

1. What is worst case scenario in case of continuing driving car for the next following days with faulty non-working auxiliary pump? Basically two days to work and back is about 100 miles in total. As I already mentioned it will be only on Tuesday, but this is my only car and I only one option to get to work. As I am understanding pump just helps to recirculate coolant for EGR and inside heater? Correct if I am wrong?

2. Are any commonly made mistakes during pump replacement that I need to know and avoid, of course If anyone had a previous experience with additional coolant pump.

[Allowencer]

Sorry, I'm not very familiar with the diesel motor. It has 2 coolant pumps? One is belt driven and one is electronic driven if I'm understanding things correctly / based on your context?

[jkeeeng]

Yes, basically lots of modern cars gor 2 coolant pumps. Main + auxiliary. Main driven from belt, electric driven from supply. It is possible used to keep going cooling process even when the engine is off.
In particularly this diesel motor it works as for cooling exhaust gases (EGR) and possibly the saloon heater.

[Allowencer]

I'm more versed on petrol engines and not diesel ones. I've heard of it, but it also depends on the make of the engine if it has a second pump. This one is called the re-circulation pump right (code V50)? Is it installed in the area between the engine and the plenum chamber front wall? If so, there really isn't any damage that can occur if this pump isn't functioning. This pump's primary function is really for 'start/stop' vehicles; I'd imagine your car has this? If I've batted 1.00 so far, let me know and I can post all the detailed notes I have on it.

[S4'ed]

It is the afterrun coolant pump. They usually fail because the motor shaft seal fails allowing coolant into the motor electrical side. These typically only run for a few minutes when you shut down a hot engine, to keep the coolant flowing to cool down the turbo bearing and minimize hotspots in the head. You can drive the car as-is, but I would replace as soon as possible. Nothing tricky about changing it...just refill and bleed the coolant system when done.