U0420Invalid Data Received From Power Steering Control Module A
- Generic OBD-II code · Network
- How the car detects it
- U0420 is stored when a listener gets frames from power steering control module A, the electric assist unit on rack or column, yet judges their content unusable. GM's 2025 tables name several listeners: the ECM tests the steering wheel information for bad counter, protection value or checksum and needs 8 failures within 18 samples for a Type C fault with no MIL; the EBCM runs similar Type C tests, and the EOCM3 assistance controller checks torque overlay and assist status (3 of 4 or 6 of 10 frames) and switches adaptive cruise off. Mazda bulletin 15-003/20 blames U0420:68 in the front camera on low voltage during cranking, which spoils the EPS centre learning; new EPS software helps. Jeep 08-094-25 (2025 Wagoneer) reflashes the EPS when U0420-00 comes with a MIL. U0131 is lost contact, U0320 software.
- What you may notice
- Adaptive cruise, lane keeping or emergency braking unavailable
- Stability control or steering warning in the cluster
- Code returns after cold starts with a weak battery
- Likely causes
- LikelyLow battery voltage during cranking corrupts steering module start-up data
- PossibleSteering module or receiving module software needs an update
- RareCorroded connector or poor ground at the steering module
- Repair
- Workshop only · Usually a job for a workshop.Typical cost: €50 – €600
- Related codes
Explanation from obdex (CC0), exactly as the app shows it. Guidance only; confirm with a workshop.