Henrijs

I got CEL and code is 17981 P1573 left engine mount solenoid valve N144: open circuit.

Serviss said that it is the one at the front of the engine, but I started to doubt because the code talks about left engine mount? I attached picture where can see the three mounts, what is the right one to change?

Thanks a lot!

MP4.2+6.0

The one you have highlighted is #14. That is called the torque support mount. It does have a motor mount type function, but mostly under load (torque)--it helps fight the rotational force on the motor when you accelerate and put the motor power down to the wheels. That mount does not have an electrical connection, so in turn you should not have a code for it. As in, that is NOT the one for your code. BUT, it may be broken in fact and need attention. You look for a crack around its circumference and dark brown stains near and below it, which is the buffering oil they put inside it that has leaked out. Not dealing with it can in turn put more stress on the main mounts. It broke on my W12 before 75K miles, and other W12 owners often report the same. It also broke on my 2000 A6 4.2 over the years. Thus, your service person may have seen the crack or oil and assumed the code was for that one.

On your question, the main mounts are ## 4 and 5. Notice on those the illustration shows what looks like a wire coming off, while it doesn't on #14. I think the left-right may be based on how you look at motor under the hood, so it would be #5. But, the diagram is saying it is the opposite when you look at the descriptions for the numbers. An electrical diagram will confirm by the "N144" notation, which is what you should look at to pin it down. Before replacing though, check the plug connection on it for corrosion and sound fit. If I recall, there is a TSB on them which may basically say the same thing.

Thus, you may have TWO mount issues overall, one the service person saw physically (if they did), and one electrical.

Henrijs

Thanks for taking the time to answer so thoroughly! I'll check the one at the front, maybe it's gone bad aswell because I can feel some vibrating from the engine.
So #4 is the one what is causing the CEL? The mount costs around 250€, so just want to be sure that I order the right one

2001 S8

A sign that the torque mount (front one/#14) is/has gone bad. At a complete stop with your foot on the brake, and the car in drive and idling. Does your steering wheel vibrate to the point you can see it vibrating? Now while at a complete stop with the car in drive and idling give the car a little gas. Does the steering wheel vibration stop? If so, your torque mount should be replaced.

I know this from personal experience. I had the steering wheel vibration issue. When I had my timing belt service done (92,000 miles), they also replaced the torque mount, as it was worn out. After replacing the torque mount the vibration was gone.

Good luck.

MP4.2+6.0

See this: Audi Workshop Manuals > A4 Mk2 > Power unit > 8-cylinder direct petrol injection engine (4.2 ltr. 4-valve RS 4), mechanics > Engine assy,cylinder block,crankcase > Assembly mountings > Removing and installing engine mountings From looking at that, plus the earlier parts diagram you posted as well as my W12 related info, Audi apparently is describing "left" and "right" for these from the perspective of sitting inside the vehicle (one of the conventions used). That makes it #4 in the parts diagram. Same as the parts description in the diagram.

Again, first check the wiring connection to it, and separately look at the torque mount visually. Also, there is also a self test available for the left and right mounts in VCDS. You activate the test and it clicks the internal mount solenoid if it is working electrically. Thus you could reconfirm wire connection and then try to activate the test to make it click. If no click (or you find it cracked with oil leaked out), it is probably bad absent a wiring issue further upstream.

nathanwind

Bumping an old thread here I realize, but having similar issue...but with the right-side motor mount (VCDS below....right-side is the passenger side for us in North America/Left-Hand Drive config).

My question is this - I've dropped the belly pan, pulled and inspected the connectors (both sides actually just to compare it to the left-side which is functioning properly), cleaned the connector, etc. I also did a visual inspection of the right-side motor mount and compared it to the left-side motor mount. There is no leaking fluid, no sag that I can see, and I took comparative measurements of left vs right motor mounts and they appear to be identical. In other words...I'm not completely convinced that it has actually "failed" structurally.

I did also check the pigtail from the vehicle, and the red input wire does appear to have ~14volts coming through it so at least makes me believe the vehicle-side wiring is functioning (well, at least the input wiring...haven't tested the line out but I'd assume it takes some feedback from the solenoid and routes it back to the vehicle).

I couldn't find any information on the TSB that was referenced, but was wondering what the TSB details specifically....anyone have info on that? That said, the other possibility it seems that remains is that the internal solenoid on the mount has failed prematurely, before the mount itself failed structurally. *If* that is the case - I don't suppose there is any way to workaround that? Even if it's putting some sort of a resistor inline to "fool" the computer?

That said, I'm not opposed to actually replacing the motor mount...but my concerns are: A) I replace the motor mount but yet the issue still persists, as possibly the TSB points to an alternate fix or cause, B) I replace the motor mount for no structural reason, but simply because of an internal electrical solenoid that has failed.

The "B" scenario I almost think would annoy me more than "A"!



VCDS---------------------------------------------------------------------------

1 Fault Found
17985 - Right Engine Mount Solenoid Valve (N145): Open Circuit
P1577 - 004 - No Signal/Communication
Freeze Frame:
Fault Status: 01100100
Fault Priority: 0
Fault Frequency: 85
Mileage: 148541 km
Time Indication: 0

Freeze Frame:
RPM: 139 /min
Load: 80.8 %
Speed: 0.0 km/h
Temperature: 96.0°C
Temperature: 56.0°C
Absolute Pres.: 0.0 mbar
Voltage: 10.160 V

MP4.2+6.0

So, cutting to the bottom line practical, if it is a main mount, have you run the VCDS self test? The one that makes the solenoids click? I know from my W12 and my old C5 4.2, I could make them click assuming all was well. Neither one had a torque mount that pretended to have the electrical control like a lot of the D3 4.2's do, at least early ones, but the main mounts did. Thus if you test it and driver's side does click but not passenger side, yet more confirm. And to totally nail it before doing work, then self test it and put a voltmeter on the passenger side leads to make sure it is getting a power signal. Except, yet more reading--I don't know if these are 14V or variable or what.

BTW, if you run test multiple times, you may have to exit module and maybe restart VCDS, sometimes even recycle the ignition. BTDT on various of these tests when I run several times.

Even if the main mount is not distorted or cracked, you do want the function for smoother running in general. Why they put it in--in addition to the hydraulic dampening that has been in them for a lot of generations now.

Emmanuel Maldonado

Did you fix your engine mounts? I just got this code