CODE: P1B1C (coolant pump mechanical malfunction)

[esssssss]

Yesterday, received a fault on the dash: "Turn off engine and check coolant level".

Pulled over and checked under the hood:

• Coolant in the reservoir was between the min and max lines.

• Engine didn't appear overly hot (operating temp normal).

• No Smoke.

My coolant gauge on the dash was perfectly in the middle where it always is (no drifting).

I drove the car home 2-3 miles, plugged it in and found the code: P1B1C (coolant pump mechanical malfunction); I clear the code.

Today, received the same fault, at the same location (about 2 minutes into my morning drive), which makes me think its an issue with the thermostat (opening/closing the t-stat at that point when the car is up to operating temp and needs to cool) versus a faulty sensor. But both seems to be a fairly common failure point reading the forums, as well as a nearby vacuum solenoid?

Is there anyway to test this more thoroughly to confirm the failure point? I have VCDS and can log, but what should I log to verify?

Thanks.

[A4Maine-iac]

More than likely the sensor is going bad in the coolant tank.

[ajrdsr]

I wouldn’t go buy parts based on my experience alone… but I had the same code on my 21’ SQ5 at 48kmiles and the dealer replaced the coolant tank under warranty and the issue was fixed. I presume the sensor was part of the tank.


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[B8A4Kevin14]

There is a TSB on the water pumps:
https://static.nhtsa.gov/odi/tsbs/20...07223-0001.pdf

You can find a lot of info here:
https://www.audizine.com/forum/showt...0#post15127720

[esssssss]

Took the car out again this evening and no fault/codes… same route plus another 5 miles…. maybe it is a sensor… but incredibly coincidental the alert popped off two days in a row at the same location

[A4Maine-iac]

Sometimes they do get a little build up and may have come off.

Nothing was changed with coolant? Also how long since its been flushed?

[esssssss]

The fault popped off again today (same spot) on the morning commute. Logged the coolant temp—it never went above 98c.

It seems to only happen after a (overnight) cold start.

I ordered a new Coolant Reservoir, but it won’t be delivered for another week.

Going to keep monitoring.

To answer your question, it’s never been flushed on my watch (owner from 30k to 42k miles). The coolant still tests well, so this wasn’t on my to do list.