Invalid Data Received From Power Steering Control Module
The U0420 code means the vehicle's onboard diagnostic system has detected: Invalid Data Received From Power Steering Control Module. This is a serious severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $50 - $500 (usually the fault behind the bad data, not the network itself)
Network codes mean modules are not communicating. You need a scanner that reads all systems to find the problem.
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Common Symptoms
- Check Engine or related warning light on
- Functions relying on data from the Power Steering Control Module may act erratically
- Often intermittent
Probable Causes (Ranked by Likelihood)
- The Power Steering Control Module is transmitting, but its data is implausible - often a failing sensor feeding it High
- Intermittent wiring fault corrupting messages Moderate
- Software mismatch after service Moderate
- Failing Power Steering Control Module Low
Common Fixes by Vehicle
What techs usually find when diagnosing U0420 on specific vehicles — tap your vehicle for the fix and the exact part:
Most makes (invalid data from a module) moderate DIY
U0420 means a module received implausible data from another control module — often a software/calibration issue or a failing sensor feeding bad values, not a wiring break. Identify which module sets it, check for TSBs/reflashes, and scan all modules for related codes. A full-system bidirectional scanner is essential to pinpoint the source.
Labor: DiagnosticFrequently Asked Questions
What does U0420 mean?
U0420 means this module IS communicating with the Power Steering Control Module, but the data it sends fails plausibility checks. Diagnose the source module first.
Can I keep driving with U0420?
Usually yes for a short period. The affected function may be degraded, and intermittent wiring faults tend to worsen - diagnose soon.
Should I replace the module for U0420?
Not first. Most communication codes are power, ground, fuse, or wiring problems. Replace the module only after those test good - modules are expensive and often require programming.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
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Scan the Power Steering Control Module itself - the invalid data usually traces to a fault code stored there.
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Fix any codes in the source module first; this code often clears with them.
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Check for recent programming or battery-disconnect events.
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If the source module is clean, monitor the specific data value flagged and follow the OEM pinpoint test.
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
Commonly Affected Vehicles
- All OBD-II vehicles - network (U) codes are standardized across makes
Related Codes
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