U0401: Invalid Data Received From ECM/PCM A
Key takeaways
- U0401 means another module, often the transmission, ABS or instrument cluster, is receiving messages from the engine computer but the data in them is flagged as invalid.
- The most common reason is another fault inside the engine computer, so read and fix the engine's own codes first.
- Drive short trips only: the transmission, cruise control or driver-assist features may shut off or fall back to a safe mode.
- Software is a big part of this code: Ford, GM and Mazda bulletins name U0401, many of them fixed by reprogramming a module.
- 66 owner complaints filed with NHTSA mention U0401, led by the Ford F-150 with 9.
What U0401 means
Another computer in your car is hearing the engine computer fine, but doesn’t trust what it’s saying. Scanners call it “Invalid Data Received From ECM/PCM A.” Modules share data over the CAN bus: the engine computer (ECM or PCM) sends engine speed, throttle position, torque and temperatures to the transmission, ABS, instrument cluster and driver-assist systems. Each message carries checks. When a receiving module gets values that are out of range, fail their checks, or arrive marked “invalid” by the engine computer itself, it stores U0401.
That last case is the common one. When the engine computer has its own fault, such as a bad throttle or pedal sensor, it often flags the affected data as invalid, and every module that uses it logs U0401. The fix is then the engine code, not the network.
Is it safe to drive?
Short trips only. Depending on which data is bad, the transmission may shift harshly or hold one gear, cruise control and driver-assist features can switch off, and some cars lose power or go into a reduced-power mode. Stay off the highway until it’s checked.
The answer becomes no if the car stalls, won’t crank, or loses power while you’re driving. Have it towed rather than risk a stall in traffic. If U0401 is only stored in history after a battery event and the car drives normally, it may be nothing; clear it and watch.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Another fault inside the engine computer (sensor, throttle, voltage code) | Read the engine computer’s own codes; U0401 clears once that fault is fixed | Depends on that repair; $100–$180 to diagnose |
| Low voltage or an interrupted crank | Battery load test; code set after a jump, a flat battery or a stalled start | $0 if it only needed a charge; $150–$350 for a battery |
| Software mismatch or a known software fault | A bulletin covers your car, or a module was recently replaced or updated | $100–$200 |
| Loose or corroded terminals, engine computer power or ground | Voltage drop test at the engine computer connector | $20–$120 |
| Damaged or wet wiring or connector at the engine computer | Inspect and test the connector and network wiring | $100–$250 |
| Failed engine computer | Power, ground, software and wiring all good, data still invalid | $800–$1,800 plus programming |
What to check first
- Read the engine computer’s own codes. If there’s a sensor or voltage code there, fix that first. A reader that only shows engine codes may not show U0401 at all; see how to read check engine light codes.
- Test the battery and charging system. A flat battery, a jump start or a cranking cut short can all leave a one-time U0401.
- Clear it once and drive if the car runs normally. If it doesn’t return in a week, stop there.
- Ask about software updates before anything else is replaced. The bulletins lean heavily toward software: Ford covers U0401 on 2017–2020 F-150, 2020 Escape and 2018 Super Duty 6.7L trucks, GM on 2024 Colorado, Canyon and Corvette, and Mazda on the 2019 Mazda3 and on 2018–2019 MX-5s when cranking is interrupted.
- Check power, ground and the connector at the engine computer before condemning it.
- Replace the engine computer last, and only if a shop has ruled out the steps above.
66 owner complaints filed with NHTSA mention U0401. The Ford F-150 leads with 9, followed by the Honda Accord and Honda Pilot with 4 each. These are owner reports, not confirmed defects.
What it costs
The cheap outcome is a charged battery and a cleared code, $0. The common outcome is fixing the engine fault that caused it or a software update at $100–$200, plus a $100–$180 diagnosis that’s often credited to the repair. The expensive outcome is an engine computer at $800–$1,800 plus programming, and it’s rarely the answer. If you want help sorting out which of your codes to fix first, ask our AI mechanic.
Related codes
U0401 often comes with an engine code that explains it, and with P0562 (low system voltage) or P0606 (engine computer processor fault) when the computer itself is the issue. U0100 means the messages stopped entirely. U0402 and U0404 are the same kind of fault for data from the transmission and gear shift modules.
What owners report to NHTSA
66 complaints filed with NHTSA mention U0401, 63 of them since 2015, across 39 different models. The component owners most often filed it under: power train.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| FORD F-150 | 9 | 2013, 2014, 2015, 2016, 2017 |
| HONDA ACCORD | 4 | 2018, 2020 |
| HONDA PILOT | 4 | 2016, 2019 |
| JEEP COMPASS | 3 | 2014, 2015 |
| HONDA CR-V | 3 | 2017, 2018, 2019 |
Manufacturer service bulletins that name U0401
110 technical service bulletins and manufacturer communications filed with NHTSA mention U0401, from 11 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- CHEVROLET CORVETTE (2024, 2025), bulletin 11010700: This service bulletin provides information to correct a customer concern of Check Engine Light or Malfunction Indicator Lamp Illuminated with DTCs U0401 and/or U1611 Set.
- GMC CANYON (2024), bulletin 11008089: This technical bulletin provides a procedure to correct the condition of Intermittent No Power or Vehicle will Hesitate DTC P0700, P0EFF, U1611, U0401.
- CHEVROLET COLORADO (2024), bulletin 11008089: This technical bulletin provides a procedure to correct the condition of Intermittent No Power or Vehicle will Hesitate DTC P0700, P0EFF, U1611, U0401.
- POLARIS SLINGSHOT SL (2023), bulletin 10237501: Polaris has determined that some Model Year 2023 Slingshot vehicles, produced between December 2022 and March 2023, could be missing the 9th digit of the model number in the ECM. The 9th digit is used for activation of h…
- FORD F-150 (2017, 2018, 2019, 2020), bulletin 10172021: SSM 48563 - 2017-2020 F-150 - No Crank/No Start, Multiple Illuminated Warning Indicators And/Or DTCs Some 2017-2020 F-150 vehicles may exhibit a no crank/no start, auto start stop inoperative, illuminated malfunction ind…
- FORD ESCAPE (2020), bulletin 10180361: Some 2020 Escape vehicles may exhibit an illuminated malfunction indicator lamp (MIL) and diagnostic trouble codes (DTCs) U0100, U0401, P166B, P1753, P0929, and/or P0919. The vehicle may also exhibit an illuminated power…
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Is U0401 the same as U0100?
No. U0100 means messages from the engine computer stopped arriving. U0401 means they arrive but the content is wrong, out of range or marked invalid. U0401 usually points at a problem the engine computer already knows about, or at software, rather than at broken network wiring.
Can a bad battery cause U0401?
It can. Low voltage during cranking can make the engine computer send bad values or reset mid-message, and some bulletins describe U0401 setting when cranking is interrupted. If the code appeared after a flat battery or jump start, test the battery and clear the code once.
Do I need a new ECM for U0401?
Usually not. Fix any other engine codes first, then check for software updates, then power and ground at the engine computer. A replacement engine computer is the last step, after all of that is done.
Why did driver-assist warnings come on with U0401?
Features like adaptive cruise, lane keeping and automatic braking use engine data such as throttle and speed. When that data is flagged invalid, those systems switch themselves off and post a warning. They come back once the engine computer's data is good again.