Hi all,
I’ve got a 2015 Audi A5 with a recurring issue related to the power steering control module (J500). The fault is U140A00 – Terminal 30 open circuit, and it disables the power steering when it happens.
It's happened twice now under very specific circumstances where I've rode the clutch for maybe a second longer than I should have, before selecting third gear. The engine cuts outs mimicking a stall, and then the power steering is gone until a garage resets the fault.
Audi performed an initial repair for £900, replacing some of the wiring. They reset the fault using their diagnostic tool (probably ODIS), and the steering worked fine afterwards — but the fault returned a week later, and they now want £3,500 to replace the steering rack, which I’m not convinced is necessary.
If the steering functions perfectly once the fault is cleared, that suggests the issue is superficial — possibly a false positive or transient electrical glitch rather than mechanical failure.
They've reset the fault again, and all is currently working, but it will fail again.
My goal is to buy a reliable OBD2 device that can clear this fault when it arises, ideally one that can access the J500 module directly and possibly run some diagnostics too.
Has anyone successfully used a consumer-level tool (OBD11, VCDS, Carista, etc.) to clear this specific fault?
Would love to know:
Which device you used
If it could access the J500 module / steering assist
If it actually cleared the U140A fault (and didn’t just read it)
Thanks in advance!
For anyone interested, this is Audi's diagnostics report:
SYS01_x_1_0715_21_GW_Info_00000
Functional checks (2)
Function test 3: SYS_8T_45_____1_0618_21_J500_FSP_00021 Time required (TU): 0.3
Result:
X
Time required (TU):
0.3 ( 2025-04-30 07:54:32 - 2025-04-30 07:54:41 )
Mouse clicks:
2
Keyboard entries:
0
Test step:
Preparation steps
Test step:
Read fault memory
Action:
Message
In the ABS control unit -J104 fault 01309 Power steering control unit / Read fault memory is stored.
Test step:
Read fault memory
Action:
Message
Faults are entered in the fault memory of the Power steering control unit -J500.
For further fault treatment work through the test plan.
Test step:
Caster
Action:
Message
End of test.
Function test 4: SPG_8K_48_____1_0511_SPGSVERSORGUNG_KL_30_A4_A5_00021 Time required (TU): 3.1
Result:
OK
Time required (TU):
3.1 ( 2025-04-30 07:54:51 - 2025-04-30 07:56:24 )
Mouse clicks:
14
Keyboard entries:
0
Test step:
Preparation steps
Test step:
Brief description of test
Action:
Message
Using this test program, you can check the following component/system: Terminal 30
Required test equipment:
Possibly VAG 1594/13 CLAMP ON TEST PROBES from VAG 1594 A Connector Test Kit.
Road test if necessary
Test step:
DTC memory
Action:
Message
The DTC memory of the Power Steering Control Module -J500- stores the malfunction U140A00 Terminal 30 open circuit .
Function call: jxxx_xx_1_0416_21_DTCs_pruefen_00000
Test step:
DTC memory
Test step:
Check fuse
Action:
Selection
Was the fuse for terminal 30 faulty and was it replaced?
Input:
No
Test step:
Check harness connector/wire 1
Action:
Message
- Check harness connector of Power Steering Control Module -J500-.
- Check the connector for:
Correct seating/loose contact;
Bent and pushed-in pins;
Widened connector terminals;
Water entry, contact corrosion;
Crushing, kinking and abrasion of the connected wiring.
Action:
Selection
Is there a malfunction?
Input:
No
Action:
Selection
- Check Ground (GND) connections of steering according to wiring diagram.
- Check wiring for short circuit to ground.
Is the wiring OK?
Input:
Yes
Action:
Message
The wiring and harness connectors are OK.
Control unit communication (UDS)
Control unit:
Power steering (LL_SteerAssisUDS)
Job status:
OKAY
Service: SinglJob_ChangDiagnSessi
Request parameters:
Response parameters:
Function call: j500_8R_48_____3_0111_21_fsp_loeschen_00021
Test step:
Mode change
Control unit communication (UDS)
Control unit:
Power steering (LL_SteerAssisUDS)
Job status:
OKAY
Service: SinglJob_ChangDiagnSessi
Request parameters:
Response parameters:
Test step:
Read DTC memory
Action:
Message
Next, the DTC memory of the Power Steering Control Module -J500- will be checked again.
Action:
Message
DTC memory is being checked.
Please wait
Control unit communication (UDS)
Control unit:
Power steering (LL_SteerAssisUDS)
Job status:
OKAY
Service: SinglJob_ReadAllDTCFreezFrame
Request parameters:
Response parameters:
Control unit communication (UDS)
Control unit:
Power steering (LL_SteerAssisUDS)
Job status:
OKAY
Service: SinglJob_ReadAllDTCFreezFrame
Request parameters:
Response parameters:
Action:
Message
The DTC U140A00 Terminal 30, open circuit is not stored in the DTC memory of the Power Steering Control Module -J500-.
Test step:
Road test
Action:
Message
To check the function, perform a road test while observing the following instructions.
- Drive off-road if possible.
