A3 Steering Angle Sensor Problem: Diagnosis & Repair

Vehicle:
Audi A3, 1.9 TDI, manufactured in 2003, 74 kW.

Here's the error:

Control unit part number: 1C0 907 379 G.

Component and/or version: ESP FRONT MK60 0101.

Encoding: 0019458

"One error found:"

00778 - Steering angle sensor (G85).

003 - mechanical fault.

The ESP light is constantly on.

Am I correct in assuming that this device is then marked as "@edit: broken"?
I now want to check if the sensor reacts to steering wheel movements; if not, then I will replace it.

Has anyone else experienced something like this before? Maybe someone has another idea for how to find the error?

Thank you very much.

You can check the steering angle in the vehicle's data log (on-board diagnostics).

Just flip through it and turn the wheel .

The new one will need to be calibrated, though. I believe there was a guide posted on this forum sometime.

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

VAG-COM, initiate basic settings... Display group numbers 60, 63, 66.

Okay, there's some news.

I performed some tests using Vag-Com. In my opinion, the steering angle is displayed correctly. When the steering wheel is centered, it shows +/- 0°, and when you turn it to the left, it goes into the positive (or negative – I don't remember which), and when you turn it in the other direction, it goes into the corresponding range. Then, quite by chance, I noticed that the lateral acceleration was exactly 0 and didn't change even while driving, and I thought that this might be the problem. However, what's strange is that the error message doesn't seem to match.

@wob-in:

Thank you for your input. Are you telling me that I should just recalibrate the device and that will fix it?

Thank you everyone.

When I then, more or less by chance, noticed that the transverse acceleration was exactly 0 and didn't change even while driving, I thought that this might be the problem. What's strange is that the error message doesn't seem to fit.


Hello.
Then check the gear sensor, but I'm sure you've already done that.

Yes, it seems like they've programmed a rather strange error detection system here.
The control unit believes that the actual value from the steering angle sensor is incorrect because it's not detecting any lateral acceleration.

Therefore, the prioritization of the two sensors in the control unit has already been described .

Best regards, Jochen.

Can someone tell me where I can find the transverse acceleration sensor in an Audi A3 (type 8L)?
What is a gear sensor?

Thank you.

Hm, "Gearsensor" would likely be a "gang sensor," and I think the engine control unit (ECU) already knows that. It's probably referring to a "gyroscopic sensor": a sensor that detects the degree to which a vehicle, aircraft, or ship is tilting or experiencing instability.

Best regards, Rainer.

And where is this gravity sensor located? Is that the same as an accelerometer? Could they perhaps be combined into a single unit?

Oops, I guess I had the wrong spelling in my head.

Okay, you meant the 'Giersensor.'

This measures movement around the Z-axis, which corresponds to steering movements.

There are dedicated sensors for longitudinal acceleration and lateral acceleration.

I'm not exactly sure where the sensor is located in the A4, but in a '98 Passat, it's in the footwell, on the front left side, in front of the central control unit for the comfort system. Perhaps it's also located there in the A4?

You mentioned that the transverse acceleration sensor didn't show anything, right?

Perhaps you could perform another measurement run and record data from all three sensors.
Then maybe you'll know even more.

Best regards, Jochen.

"I apologize for the confusion; this is about my friend's car, specifically an Audi A3 8L 1.9 TDI PD with 74 kW, as indicated in the title."

I suspect the problem isn't with the steering angle sensor, but somewhere else, and I don't want to blindly replace parts without being sure they are the correct ones first.

Does your assumption make sense? Based on what I see, I cannot confirm your assumption, let alone understand it.

http://wiki.ross-tech.com/index.php/00778

Okay, my assumption is that the steering angle is displayed correctly on the instrument cluster, and the lateral acceleration always remains at 0.

Okay, so I'm going to try to initiate a basic sensor reset and then check if the sensor is properly mounted (well, it should be, since the values are being displayed correctly).

What does "suspension geometry incorrect" mean?

mserge wrote:

What does "suspension geometry incorrect" mean?

Wheel alignment > Measuring wheel alignment.

Regarding movement in space:

to nod up and down = to nod.
"Rolling to the right and left" refers to rolling (especially problematic for container ships because their cargo can shift and fall overboard; therefore, ships are usually turned into the wind to minimize rolling).
pitching around the longitudinal axis = yawing

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

Thanks to your help, I hopefully solved the problem yesterday. When I asked my girlfriend if there might be a problem with the suspension, she told me that the steering wheel has been misaligned while driving straight for some time. After checking, I discovered a slow leak in the right front tire, and the tire pressure was down to 1.1 bar. I had the tire repaired (yes, even yesterday evening) and then initiated a basic adjustment, and now the warning light is off.
So far, everything seems to be working fine. If the problem reappears, I will let you know.

Thank you again to everyone involved here.

mserge wrote:

Thank you again to everyone involved here.

Thank you also for the feedback.