Hello, I have a battery drain with a 2015 Audi A5 with the car shut off. I can hear three noises coming from the engine compartment that repeat every 15 seconds and this is likely causing the drain. See attached video to listen. I would describe the noises as a "beep", "click", and electric motor sound. The beep is coming from the middle back of the engine. The click is likely a relay underneath the wiper fluid container, and the motor sound is coming from a component on the right side of the engine (see picture). I tried disconnecting the battery and starting and restarting the engine but the noises continue. Initially there was no code but then it I got a P2025 (Fuel Vapor Temp Sensor). I will likely try changing this but looking for any help on what's going on here before I do. Thanks.

 

B8.5 2.0T, and a pic of what appears to be the afterrun coolant pump, the first thing that comes to mind is was it replaced yet under the fire hazard safety recall for those things. But then you say right side of the engine, where there is no coolant routing. If this were a V6, I'd think maybe it was the V50 pump. But US B8.5 A5 don't have V6s. Maybe back up and guide us in to what you're looking at more. Take a picture where we can see the actual engine bay and mark on it a spot where the way zoomed in pic is looking.

It could be the electric coolant shutoff valve between the engine and the heater core; that sits behind the engine.

Relays are in the ECM box. Remove the washer fluid filler neck and then you can open the ECM box to get better audio from the relays, if you think it's one of those.

P2025 on a CPM engine is "EVAP Fuel Vapor Temperature Sensor Performance". That's going to have to do with the J909 / G400 devices back at the fuel tank. Nothing in the engine bay.

Nothing in the audio track was recognizable. Sounded like something trying to wind up. But didn't seem like the sound of the afterrun pump as I have it on my B8.0. But B8.5 use a different pump.

 

Thanks SMac770. My mistake, the electric motor noise is coming from the back left of the engine and I've attached better pictures. I'm pretty sure it's the after run coolant pump like you mention. It is connected to a coolant hose. I also cleared to the P2025 code and it did not come back so maybe that's unrelated. I can't isolate where the 1 second "beeping" noise is coming from but it seems to be also from the back of the engine near the after run coolant pump. After the car is warmed up and I shut it down, the after run coolant pump runs continuously and the 1 second beeping noise comes on every 35 second. After the car cools down the cycle changes to a 15 sec cycle as follows. Time 0s: 1s beep followed by relay click. Time 5s: relay click followed by 2s of elec motor run. Time 15s repeat. Time 30s repeat...

I opened the relay box and it appeared one of the "645" relays was clicking. I replaced it and nothing changed. I'm now considering changing both "646" relays and the other "645" relays.

I also checked the records on the car and the recall for the pump was completed in 2019.

 

My V51 afterrun coolant pump starts up on engine off, as expected, and it just hums for however long it runs, maybe up to 10 minutes. The fans used to come on too, and probably should. But have (almost) never come on since they did the ECM update for the change in crankcase vacuum (oil consumption step 1). The only other noises I have from the engine bay is the throttle valve doing its calibration, as it does on engine off. That's a whine and beep and such, but it's done within 15 seconds.

You might take a paint stirring stick (like you get from Home Depot for free) or broom stick and hold one end to your ear and one end to various points of interest and see if you can hear the noise source in that isolated manner.

The 645 cubes (used to be 643), one is for the power to various engine components, one provides power only to the HPFP regulator valve (on top of the HPFP), at least for the B8 Gen2 TFSI. The 646 half cubes (used to be 404) are the starter relays. Not likely to be involved in whatever this issue is.

click click thump ... thump whine startup is what I hear if I turn the volume to the max. But I can't be sure what it is making the noise. If the noise persists multiple cycles, the easy thing would be to unplug stuff until it stops. Start with the throttle valve, since it's right there, but then next would be the afterrun pump. Then maybe the coolant shutoff valve (look at the hoses from the firewall (heat exchanger) to the engine; one will have a electrically operated cutoff valve along it.

I also don't have a B8.5 so I don't have that afterrun pump, or a CPM engine. It might well be "normal"? Someone with a CPM would have to respond. If the noise is the pump, I'd probably inspect that harness connector, make sure nothing looks burnt.

 

I'll take a look at my daughters Q5, it has a CPMB engine. First thing I thought of was either the relay for the Coolant pump sticking on or the temp sensor failing causing it to stay on and drain the battery.

 

CPM engine V51 pump is powered by the fuse 7, which powers many devices in the engine bay (motor mounts, V51 pump, the cold start injector in the IM, turbo N75 and N249, N422 coolant shutoff valve, N80 evap purge valve, etc.). The fuse is powered by the J271 cube relay in the ECM box; this is the one in the middle, above the outside end of the small fuses row. The other cube, to the inside of the starter relays, is the J757 relay, which gets power from the J271, and is only energized when the engine is spinning.

J271 > lots of stuff
J271 > fuse 7 > V51 and many other things
J271 > J757 > fuse 14 > ignition coils
J271 > J757 > fuse 5 > N276 HPFP regulator valve (the 2-pin on top of the HPFP)

The other two pins on the V51 pump are the PWM duty cycle control and error feedback signal with the ECM, and the ground line to chassis.

059 121 012 B was the p/n of the bad pump. The current pump was 8K0 121 601, but is now 06D 121 601. Apparently the bracket for the pump keeps changing; appears the bracket is specific to each pump variant.