U0406 code meaning
Invalid Data Received From Fuel Injector Control Module
Network system Generic code U04xx codes Check engine light
What U0406 means
U0406 means a receiving controller, normally the ECM/PCM, gets messages from the fuel injector control module that arrive but fail its checks: wrong counter, checksum, range or a signal marked invalid. Ford's 2012 OBD summary shows the U04xx principle with U0401: the TCM stores it when the ECM sends invalid or faulted torque or pedal data. A separate injector module exists only on some designs; GM's 2013 bi-fuel CNG Silverado/Sierra uses an FICM that switches the injectors and passes rail pressure and temperature to the ECM over serial data. No manufacturer documents U0406 publicly. As fuel delivery affects emissions, CARB requires such inputs to be monitored and a MIL is likely. U0105 means lost contact, U0306 a software mismatch.
U0406 at a glance
- Check engine lightYes, usually on
- Emissions testCan fail
- Limp modePossible
- Repair difficultyHard
- Typical labor1 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0406
- Check engine light on
- Rough running, misfire or hard start
- Reduced power
Common causes of U0406
- PossibleCorroded or loose connector, damaged bus wire to the injector module
- PossibleLow supply voltage at the injector module
- PossibleSoftware levels of injector module and ECM do not match
- Less likelyInjector control module internally faulty
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Fuel injector control moduleEngine control moduleCAN bus wiring
What each part of U0406 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 06 | The exact fault in that area. |
What to do next
- Note U0406 and any other codes stored with it: several codes together often point to one cause.
- Check for loose connectors and damaged wiring around the parts the code names.
- Check open recalls for your car: some faults are fixed for free by the dealer. Enter your VIN.
- Clear the code only after the repair. If it comes back, the fault is still there.
Buying a used car? Scan it for stored codes before you pay. A recently cleared memory can hide a problem.
Questions about U0406
What does U0406 mean?
U0406 means "Invalid Data Received From Fuel Injector Control Module". U0406 means a receiving controller, normally the ECM/PCM, gets messages from the fuel injector control module that arrive but fail its checks: wrong counter, checksum, range or a signal marked invalid. It is a generic code, so it means the same on every make.
Is it safe to drive with U0406?
Drive gently and only to a workshop. With U0406 the car can go into limp mode (reduced power) to protect itself.
Will U0406 fail an emissions test?
Yes, it can. U0406 is emissions-related, so most inspection programs fail a car while it is stored or while the check engine light is on.
How hard is U0406 to fix?
Difficulty: hard. A typical repair takes 1 to 3 hours of work. This is a job for a workshop.
Will U0406 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.