Clutch position sensor (G476)

Hello,

"I read these error codes from an A4 B8. After a short period of being parked, the car would not start again. I suspect that the clutch master cylinder or the sensor inside it (G476) is defective. Unfortunately, we were unable to test whether the car starts with the gear lever in neutral, as the error did not reappear after that."


Address 01: Engine Control Module (J623-CAGA)
5 error codes found:
5597 - Clutch position sensor (G476).
P3082 00 [036] - implausible signal.
Occasionally - unconfirmed - checked since last deletion.
Environmental conditions:
Error status: 00000001
Error priority: 2
Error frequency: 2.
Mileage: 225,319 km
Date: 2021.05.15
Time: 17:49:39

Motor speed: 1142.00 rpm.
Normalized load value: 69.0%
Vehicle speed: 8 km/h
Coolant temperature: 50 °C.
Intake air temperature: 13 °C
Atmospheric pressure: 960 millibars.
Voltage at terminal 30: 14.340 V.
Lost learning counter via OBD: 40.
Crankshaft speed: 1142.0 rpm.
Vehicle speed: 8.02 km/h
Outside temperature: 11.0 °C
Board voltage, class 30: 14340 mV.
Bus Diag at Node 0 - Bits 0-7: 0
Limit: Accelerator pedal: 89.4 Nm.
Control unit temperature: 22.7 °C

4377 - Control unit, electric parking brake.
U1010 00 [047] - Please read the error memory.
[New Feature! Extended UDS error code information is supported only by the current generation of hardware.]
confirmed - checked since last deletion.
Environmental conditions:
Error status: 00000001
Error priority: 6
Error frequency: 28
Mileage: 225,317 km
Date: 2021.05.14
Time: 10:07:46

Motor speed: 0.00 rpm.
Normalized load value: 0.0%
Vehicle speed: 0 km/h
Coolant temperature: 19 °C
Intake air temperature: 16 °C
Atmospheric pressure: 960 millibars.
Voltage at terminal 30: 12.020 V.
Lost learning counter via OBD: 40.
Crankshaft speed: 0.0 rpm.
Vehicle speed: 0.00 km/h
Outdoor temperature: 12.0 °C
Board voltage, class 30: 12020 mV.
Bus Diag at Node 0 - Bits 0-7: 0
Limit: Accelerator pedal: 220.0 Nm.
Engine control unit temperature: 22.8 °C

4985 - Spark plug, cylinder 2 (Q11)
P0672 00 [039] - Electrical fault in the circuit.
Unconfirmed - checked since last deletion.
Environmental conditions:
Error status: 00000001
Error priority: 2
Error frequency: 1.
Mileage: 225,317 km
Date: 2021.05.14
Time: 10:11:55

Motor speed: 846.50 rpm.
Normalized load value: 40.4%
Vehicle speed: 0 km/h
Coolant temperature: 19 °C
Intake air temperature: 14 °C
Atmospheric pressure: 960 millibars.
Voltage at terminal 30: 11.980 V.
Lost learning counter via OBD: 40.
Crankshaft speed: 846.5 RPM.
Vehicle speed: 0.00 km/h
On-board voltage, class 30: 12080 mV.
Coolant temperature: 19.6 °C
Indicator status bits 0-7: 0.
Indicator status bits 0-7: 176
Preheating time: 0 ms.
Fuel temperature: 15.4 °C

4986 - Spark plug, cylinder 3 (Q12)
P0673 00 [039] - Electrical fault in the circuit.
Unconfirmed - checked since last deletion.
Environmental conditions:
Error status: 00000001
Error priority: 2
Error frequency: 1.
Mileage: 225,317 km
Date: 2021.05.14
Time: 10:11:55

Motor speed: 846.50 rpm.
Normalized load value: 40.4%
Vehicle speed: 0 km/h
Coolant temperature: 19 °C
Intake air temperature: 14 °C
Atmospheric pressure: 960 millibars.
Voltage at terminal 30: 11.980 V.
Lost learning counter via OBD: 40.
Crankshaft speed: 846.5 RPM.
Vehicle speed: 0.00 km/h
On-board voltage, class 30: 12080 mV.
Coolant temperature: 19.6 °C
Indicator status bits 0-7: 0.
Indicator status bits 0-7: 176
Preheating time: 0 ms.
Fuel temperature: 15.4 °C

5599 - Signal for ignition interlock device.
P1724 00 [229] - Short circuit to ground.
Warning light ON - unconfirmed - checked since last reset.
Environmental conditions:
Error status: 00000001
Error priority: 2
Error frequency: 1.
Mileage: 225,319 km
Date: 2021.05.15
Time: 17:49:36

Motor speed: 872.00 rpm.
Normalized load value: 21.2%
Vehicle speed: 24 km/h
Coolant temperature: 50 °C.
Intake air temperature: 13 °C
Atmospheric pressure: 960 millibars.
Voltage at terminal 30: 14.320 V.
Lost learning counter via OBD: 40.
Crankshaft speed: 872.0 rpm.
Vehicle speed: 25.13 km/h
Accelerator pedal position: 0.00%
Board voltage, class 30: 14320 mV.
Torque limit: 167.3 Nm.
Starter control: Deactivation conditions. Bits 1-7: 1.
Starter control: Interlock or P/N signal bits 0-7: 81


Error code 5599 indicates a problem with the starter interlock signal.
4377 - Control unit for electric parking brake; I suspect the problem might be caused by a faulty signal from the clutch actuator?

Perhaps someone else has encountered a similar problem and can help me.

Thank you very much and best regards.

Hello and good evening.

Did the warning message "Press clutch pedal" appear when starting the car?

It could very well be the switch. But you can check that yourself.

However, there is also the possibility of a clutch that has worn out gradually. As the clutch wears down, the travel distance of the clutch slave cylinder decreases, which means that the sensor at the clutch master cylinder is no longer activated.

Then it won't start.

Since the error occurs only sporadically, this should be kept in mind when investigating potential sources of the problem.

How is the clutch condition at 225,000 km?


What engine/transmission combination are we talking about?





Best regards,

Michael.

Hello,

I've told the owner for now that if the problem happens again, he should start the car in neutral.

The engine/transmission combination is a CAGA with a six-speed transmission (the exact transmission code is currently unknown).

I assume you're checking the switch either through actuator diagnostics or by measuring directly at the pins?

These models experienced issues with the ball joint and release lever. These parts were modified by the manufacturer after 2010.

But keep this information in mind as a last resort if all other troubleshooting steps fail to identify the error.

The switch should be testable within the main distribution board.



Best regards,

Michael.

Hi there,
"On the Audi A4 8K (CJCD, manufactured in 2014), the engine will not start without pressing the clutch pedal. This indicates that the sensor for the clutch position is being read. Therefore, you will likely experience the same issue with your vehicle's year of manufacture."
A question for Michael:

Quote:

However, there is also the possibility of a slowly worn clutch. Due to the wear on the clutch, the stroke of the clutch slave cylinder decreases, so that the sensor at the clutch master cylinder is no longer activated.

Could you please clarify something? It's already understood that as the friction lining wears down and the slave cylinder adjusts itself, the entire slave cylinder assembly becomes "shorter." However, the effective working range should remain the same length and only shift its position. The design must be able to last for the entire lifespan of the clutch. Therefore, even with an older clutch, I would expect the master cylinder to be activated when the clutch is fully depressed.g
Herbert.

Hello Herbert,

I completely agree with your expectations, and I'm not even sure if that was Audi's intention. In practice, when the master cylinder reaches its "end-of-life" stage, there is more brake fluid in the system than with a new clutch.

This is enough to allow you to press the clutch pedal down with what feels like normal resistance, but the clutch master cylinder will reach its end position between the second and third hall sensors, and the message "Press the clutch pedal" will appear.

During the ADAC technical training, the instructors opened the bleed screw on the slave cylinder. This allowed the clutch pedal to reach the third Hall sensor again, and the vehicle started.

I hope I explained it in a way that is somewhat understandable.


Edit: Update - I just spoke to them on the phone again.

Vehicles manufactured before 2010 were affected by this issue, but only if a clutch cylinder from a specific supplier was installed. The main cause was the worn-out release levers. Since these vehicles already had problems with the release levers and pins, the parts were repeatedly revised and changed starting in 2010. In practice, customers usually noticed a worn clutch before they could no longer start the vehicle as a result.


Conclusion: So, it's a relatively rare issue. In most cases, the problem is with the switch or wiring.


Best regards,

Michael.

Hello,

What type of sensor is installed in yours?

If you're referring to the external sensor located at the bottom of the pedal, it's very easy to adjust: Pull the plastic actuator piece with the round knob all the way out and depress the clutch once.

If it's a hydraulic pressure switch on the master brake cylinder: I would first check its wiring for damage caused by rodents, disconnect the connector, and see if there is any corrosion. Since you haven't mentioned anything about clutch problems, I assume the mechanical components themselves are in good condition.

Best regards, Rainer.