Power steering fault - Can an OBD reader reset it?

[lemonjellyking]

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.

[spartacus 68]

Not aware of specific OBD readers that will clear what is a very specific fault. VCDS will see it and you can clear the DTC.

Side note, how old is the battery? These cars are sensitive to battery degradation, and wouldn’t put it past Audi not to have checked. A cheap multimeter is handy. Get AGM and code it to the car if it’s in any way suspect.

For VCDS, you can get a 3-VIN package from Gendan for £222. Personally, get one with a case. What does that get you? Access to Rosstech software updates for life, update to OBD dongle on occasion. You just need a cheap laptop to run it on. Worth its weight in gold. https://www.gendan.co.uk/product_VCV23NC.html