U0478: Invalid Data Received From Restraints System Sensor H
What to do
The airbag warning light may be coming and going rather than staying on. That does not mean it is nothing — it means the fault is intermittent, which is harder to find, not less serious.
You can help more than any test here, and it costs nothing: notice when it happens.
- Does the light come on only after you have been driving a while, or only on the first cold start of the day?
- Does it disappear again on a different day, or after the car has stood?
- Does it appear on rough roads, or after a particular bump?
Write down what you notice and give it to the garage. These sensors sit at the front of the car and go through enormous temperature swings — hot after a motorway run, cold overnight, thousands of times — and connections work loose in a way that makes contact when cold and loses it when hot, or the other way round. Knowing which tells a technician where to look.
Do not accept "we cannot find anything wrong" as the end of it. The car stored the fault because a check genuinely failed. A system that is unreliable intermittently will be unreliable in a crash.
What this code means
A restraints system sensor is reporting a value that cannot be accepted as true. See U0471 for the family's framing and U0452 for the safety rules.
The version of this fault that is hardest to find is the intermittent one, and it has a characteristic worth recording because it points straight at the cause.
A crash sensor at the front of the vehicle lives through a temperature range nothing in the cabin experiences — heat-soaked to well above ambient after a motorway run and a shutdown, then down to whatever the night offers, thousands of times. Solder joints, crimps and connector contacts all move slightly with each cycle, and a joint that has been worked loose over years makes contact when cold and loses it when hot, or the reverse.
So the diagnostic question is not what the fault is but when it happens, and it is one the owner can answer for free:
- Does the warning appear only after the car has been running for a while, or only on the first start of a cold morning?
- Does it clear itself on a different day?
- Does it appear on rough roads, or after a particular speed bump?
Any of those answers is worth more than a workshop test on a cold, stationary vehicle, because an intermittent fault is not present when the tester is looking, and a system that passes every check while a code sits stored in memory is exactly this.
The practical consequence is that a stored intermittent restraints fault should not be dismissed because it cannot be reproduced. The stored code is the evidence. The sensor circuit failed a check at some point, and a system that intermittently cannot be trusted intermittently will not protect anybody.
Likely causes
Start here
- Intermittent wiring fault · moderate
- Corroded or loose connector · easy
- Heat damage to sensor or wiring · moderate
- Water ingress into connector · moderate
Less common
- Impact sensor disturbed during body repair · moderate
- Faulty restraints control module · specialist
Symptoms
Components involved
Information, not instruction
CarGeek is a reference, not a service manual. Its pages are written from public sources and from what other people have found, never from a manufacturer's own service information, so they can be wrong or incomplete for your particular vehicle. Some of what they describe carries real risk: high voltage, fuel under pressure, stored energy, hot and moving parts.
Have anything you intend to act on checked by a trained person against the manufacturer's own procedure for your vehicle. Nothing here replaces that procedure.
Community experience
Be the first to write this up
Nothing posted about this yet. Whatever you found is worth writing down — even a dead end saves someone the same afternoon.
What makes one worth reading:
- The car — make, model, year and engine. The same fault behaves differently on each.
- What you measured, not only what you replaced.
- What actually fixed it — or that nothing did, which is worth knowing too.
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