Hello,

I have a second hand 2020 Ford Focus (69 plate). The steering felt great when we bought it, however it intermittently has different weight when steering. This gives it a bit of a sensation of driving on ice, and like there's no grip.

I bought a VLinkerFS OBD2 cable and connected forscan and see three DTC's for the power steering: U3003 (battery voltage), C1B00 (Signal compare failure) and P0635 (Signal shape/waveform failure). Additionally, the steering angle when the wheel is straight is about -10 degrees

I had it aligned on the front wheels maybe half a year ago, I've seen a post on here describing very similar symptoms (heavy steering, wiggly back end, icy driving sensation) where a full alignment fixed it for them, does that seem worth a go? Or does it look like the battery/voltage regulator might have cooked my steering electronics?

Thanks

Anyone got any ideas?

My best as no one else has replied:
Charge, test and/or change the battery (how old, always living on borrowed time?)
Get the physical setup checked and corrected first (Kwik Fit do free check BUT will always say needs adjusting but if it is within tolerance you don't need to bother?)
i.e get the steering alignment checked and steering wheel lined up correctly.
Reset steering wheel sensor parameters in Forscan if necessary (I'm guessing here)

Beyond that, I don't understand the other codes - does anyone?

These DTCs are not active and are 4 to 5 months old. Simply remove them and see whether they return in the near future.

As far as I can see, none of these DTC codes are critical or active. Therefore, I do not expect them to be related to your actual problem.

The issues you describe are quite common on the Focus MK4. Replacing the entire steering rack is usually the only way to fix them.

Ouch!

On 2/6/2026 at 10:26 PM, Shearers said:

My best as no one else has replied:
Charge, test and/or change the battery (how old, always living on borrowed time?)
Get the physical setup checked and corrected first (Kwik Fit do free check BUT will always say needs adjusting but if it is within tolerance you don't need to bother?)
i.e get the steering alignment checked and steering wheel lined up correctly.
Reset steering wheel sensor parameters in Forscan if necessary (I'm guessing here)

Beyond that, I don't understand the other codes - does anyone?

Thanks, I'll check the battery, not sure if it's the original. I checked it's voltage after a couple of (25 mile round trip) commutes last week and it was around 12.2-12.5 volts, I figured it might be better to check after a longer drive? With the engine running and radio/heating etc all on, voltage across it was 14.8, so I think the alternator is ok. I need to get someone to faff around with electrics in the car while I measure it so I can check the regulator.

I've booked it in for a 4 wheel alignment check on monday. The steering wheel does settle may 3-5 degrees to the left when driving straight, so I get the feeling it's probably not quite aligned.

I have reset the DTC's and had a go a rebooting related modules, it didn't seem to make a difference. I couldn't run the PSCM calibration, it kept failing (service procedure not supported), but the ABS steering angle sensor calibration ran, but again it didn't feel any different.

Failing that I'll take it to get it's suspension checked. I took it to a garage maybe 6 months ago who did the front wheel alignment after checking the suspension and they found nothing, but the diagnostics I took it too a couple of weeks ago said the front lower wishbone bushings were starting to crack. My understanding is that is often the case so I plan to get it up on ramps myself and check when I can.

These DTCs are not active and are 4 to 5 months old. Simply remove them and see whether they return in the near future.

As far as I can see, none of these DTC codes are critical or active. Therefore, I do not expect them to be related to your actual problem.

The issues you describe are quite common on the Focus MK4. Replacing the entire steering rack is usually the only way to fix them.

Thanks, I've removed them. After some calibration/rebnooting, there were some ABS DTC's complaining about lost contact with the PSCM, but I assume that was just because of the rebooting. Yeah the garage I took it to recently suggested they would replace the rack if a battery replacement/recalibration failed. It's drivable so I think I'll do that if it gets any worse.

I'll update this thread if I have any more info or find a solution. Thanks for the replies all!