U0420: Invalid Data Received from Power Steering Control Module
The Power Steering Control Module is present on the data bus but the values it reports are implausible — out of range, frozen, or failing the checksum or rolling-count check. The receiving modules reject the data. Power-steering assist may be reduced or disabled. Causes include a faulty sensor feeding the module, internal computation errors, a software or calibration mismatch after a repair, or bus interference corrupting the frames.
What U0420 means
U0420 is a generic OBD-II network code in the invalid data & software group. In plain English: a module received data that didn’t make sense from the Power Steering Control Module.
- Check engine light
- Usually on
- Emissions-related
- No
- Limp mode possible
- Not typical
- Drive cycle to clear
- Not required
Get it fixed
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Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Common causes
- 01EPS module internal faultPossible
- 02CAN corruption causing checksum errorsPossible
- 03Gateway module routing CAN messages incorrectlyLess likely
Can I drive with U0420?
Drive carefully and get it checked soon.
Steering assist may drop out, making the wheel heavy at low speed. Avoid driving if steering becomes very heavy or erratic.
Why we rate it urgent
- Steering assist may be reduced or lost
- Turns on the check engine light
Severity is our rule-based rating from the code’s flags in OBDex and the system it affects, not an inspection of your car. If the check engine light is flashing, or you notice overheating, low oil pressure, or brake or steering problems, stop driving and get help.
How to diagnose U0420
- 1
Confirm the code and save freeze-frame data
Read the codes with an OBD-II scan tool and note every code, not just U0420. Save the freeze-frame data (speed, load, temperature when the fault set) before clearing anything; it tells you when the fault happens.
- 2
Check for related codes first
Look for U0521. Related codes often share a cause; a circuit or sensor code usually needs fixing before a performance code like this one.
- 3
Check module power, ground and the data bus
Confirm the module named in the code has battery voltage, ignition feed and a good ground. With the battery disconnected, a healthy CAN bus usually measures about 60 ohms between CAN-High and CAN-Low at the OBD port. Inspect connectors for corrosion and pushed-out pins.
- 4
Test the likely causes in order
Start with the most likely cause and work down: EPS module internal fault; CAN corruption causing checksum errors; gateway module routing CAN messages incorrectly. Test before replacing parts.
- 5
Check for recalls and service bulletins
Look up recalls for your exact vehicle with its VIN, and ask a dealer about technical service bulletins (TSBs). Manufacturers sometimes issue software updates or extended warranties for known faults.
- 6
Clear the code and verify the repair
After the repair, clear the code and drive the car under the conditions in the freeze-frame data to confirm it does not return.
U0420 repair cost estimate
Estimate, not a quote. Labor times are typical ranges for this code from OBDex, and $125/hr is an assumed rate. Shop rates and labor times vary by vehicle and region. Diagnosis time may be billed separately.
- DIY difficulty
- Hard
- Good DIY job?
- Usually a shop job
Involved testing or major parts. Most owners use a shop.
Parts and systems involved
- Power steering module
- CAN bus wiring
U0420 FAQ
What does U0420 mean?
U0420 means “Invalid Data Received from Power Steering Control Module”. The Power Steering Control Module is present on the data bus but the values it reports are implausible — out of range, frozen, or failing the checksum or rolling-count check. The receiving modules reject the data. Power-steering assist may be reduced or disabled. Causes include a faulty sensor feeding the module, internal computation errors, a software or calibration mismatch after a repair, or bus interference corrupting the frames.
Is U0420 serious? Can I keep driving?
We rate U0420 as urgent severity. Drive carefully and get it checked soon. Steering assist may drop out, making the wheel heavy at low speed. Avoid driving if steering becomes very heavy or erratic.
What causes U0420?
The most common causes, from most to least likely: EPS module internal fault; CAN corruption causing checksum errors; Gateway module routing CAN messages incorrectly. Test before replacing parts, because several causes can set the same code.
How much does it cost to fix U0420?
Typical labor is about $125–$750 at an assumed $125/hour shop rate, plus parts. That is an estimate, not a quote: labor times and rates vary by vehicle and region, and diagnosis may be billed separately.
Can I fix U0420 myself?
DIY difficulty is hard. Most owners leave this to a shop because it needs involved testing or specialist tools. Always confirm the cause before buying parts.
Will U0420 clear itself?
If the fault was intermittent, the warning may go off once the computer stops seeing it, but the code stays in memory. Fix the cause; clearing the code alone doesn’t repair anything.