U0551 code meaning
Invalid Data Received From Impact Classification System Module
What U0551 means
An impact classification system module helps the restraint system judge what kind of collision is under way, for example frontal, side or angled, and how severe it is, so that the right airbags and pretensioners fire at the right stage. U0551 means another module, typically the airbag or restraint controller, receives messages from this unit whose content fails its plausibility or integrity checks. No manufacturer has published a description or setting criteria for this code. Patents on bus-connected crash sensing such as US7832762 show why such traffic is protected: deployment decisions travel over the network to the protection devices. With the classification input in doubt, the airbag warning lamp comes on and the system cannot rely on that information. Treat it as a safety fault; a silent module gives U0250.
U0551 at a glance
- Check engine lightUsually not
- Emissions testNot an emissions code
- Limp modeNot expected
- Repair difficultyWorkshop only
- Typical labor0.5 to 3 hours
- Clears after repairWhen cleared with a scanner
Symptoms of U0551
- Airbag/SRS warning lamp on
- Restraint system message in the instrument cluster
- Passenger airbag status indicator behaving abnormally
Common causes of U0551
- PossibleInternal fault in the impact classification module
- PossibleModule or restraint controller not configured/programmed after replacement or crash repair
- Less likelyDamaged wiring or connector after collision or interior work
Check the most likely causes first. Replacing parts by guesswork is the most expensive way to clear a code.
Parts involved
Impact classification module
What each part of U0551 means
| U | Network system: communication between the control modules (CAN bus). |
| 0 | Generic code: it means the same on every make (SAE standard). |
| 51 | The exact fault in that area. |
What to do next
- Note U0551 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 U0551
What does U0551 mean?
U0551 means "Invalid Data Received From Impact Classification System Module". An impact classification system module helps the restraint system judge what kind of collision is under way, for example frontal, side or angled, and how severe it is, so that the right airbags and pretensioners fire at the right stage. It is a generic code, so it means the same on every make.
Is it safe to drive with U0551?
U0551 does not normally turn on the check engine light by itself. Watch for the symptoms above and have it checked soon.
Will U0551 fail an emissions test?
U0551 is not an emissions code, so on its own it usually does not fail an emissions test. Other stored codes or a lit check engine light still can.
How hard is U0551 to fix?
Difficulty: workshop only. A typical repair takes 0.5 to 3 hours of work. This is a job for a workshop.
Will U0551 clear itself after the repair?
Clear the code with a scanner after the repair. If the fault is fixed, it does not come back.