U0420

Invalid Data Received From Power Steering Control Module A

Q: Is it safe to drive with U0420?

Short trips are usually possible, but the steering can suddenly feel much heavier if assist drops out. Have it diagnosed quickly, especially before highway or heavy-traffic driving.

Q: Can I just clear U0420?

You can clear it, but if the module is still sending bad data the code returns and assist can fail again. Fix the cause first.

Communication network Generic OBD-II Medium

What it means

U0420 is a network communication code: another module is receiving data from the power-steering control module that is missing, corrupt, or out of range. The steering module and bus are talking, but the values don't make sense. Because it involves power steering, it can affect assist — the wheel may feel heavy or lose help — so it's worth diagnosing promptly.

Medium

Can I keep driving? Usually drivable, but power-steering assist may reduce or cut out and make the wheel feel heavy — get it checked promptly.

Real-world scan data

Seen in

206

scans in the past year

Found in

<0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of U0420 scans

U0415in 24.8% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

Common symptoms

What you'll notice

Power-steering warning light or message on the dash
Steering feels heavy or assist comes and goes
Check-engine or other module warning lights may also be on
Occasional loss of steering assist at low speed or startup

Common causes

Most likely first

Fault or internal failure inside the power-steering control module sending corrupt dataLikely
Wiring or connector problems on the communication (CAN) bus to the steering moduleCommon
Low or unstable system voltage or a weak battery/groundCommon
Software mismatch after a repair or module replacementLess often

How to diagnose & fix

Work through it in order

Read all modules for codes and note freeze-frame data — treat any lost-communication codes first.
Check battery voltage and grounds; a weak battery often corrupts module data.
Inspect wiring and connectors between the power-steering module and the network bus for damage or corrosion.
Test the CAN bus for the steering module; repair open, shorted, or backed-out pins.
If wiring and power are good, the power-steering module itself is the likely fault — verify with manufacturer tests before replacing.

FAQ

Quick answers

Is it safe to drive with U0420?+

Short trips are usually possible, but the steering can suddenly feel much heavier if assist drops out. Have it diagnosed quickly, especially before highway or heavy-traffic driving.

Can I just clear U0420?+

You can clear it, but if the module is still sending bad data the code returns and assist can fail again. Fix the cause first.

Read & clear U0420 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX