U0555: Invalid Data Received From Remote Start Module
What to do
The car drives normally. Remote start may simply refuse to work — and a system that refuses because it cannot verify its own conditions is behaving correctly.
If remote start was fitted after you bought the car, go back to whoever installed it. Aftermarket kits splice into the car's own circuits and that join is where these faults nearly always are. It is their work, not the manufacturer's.
One thing to take seriously: if the engine has ever started when you did not ask it to, stop using the remote function entirely until it has been checked. An engine starting unattended in a closed garage is the risk, and it is worth being blunt about.
And if the car's battery goes flat over a few days of standing, mention it — an installation that keeps the car awake is the commonest real fault behind this.
What this code means
The remote start module is broadcasting data that cannot be accepted as true. See U0400 for what an invalid-data code is and why the module it names is usually the messenger rather than the culprit.
Remote start is the function most often added to a car rather than built into it, and that single fact accounts for most of these codes.
A factory system authenticates a request, checks a long list of conditions — bonnet closed, transmission in park, no faults that would make running unsafe — and then starts the engine with the vehicle locked and immobilised. Every one of those checks depends on data from elsewhere, so this module publishes a state assembled from other modules' reports.
An aftermarket kit does the same job by splicing into the same circuits, and it is where the trouble usually is. Poor splices, a bypass module that defeats the immobiliser, and installations that keep the network awake are the three common faults — and all three are the installer's to fix rather than the manufacturer's.
The safety logic is worth respecting rather than working around. A system that refuses to start remotely because it cannot trust its own preconditions is doing exactly what it should. The danger case is the opposite one — an engine that starts when it should not, in a closed garage, or with the vehicle not properly secured. A remote start behaving unpredictably should be disabled until it is repaired, not left to see what happens.
Likely causes
Start here
- Aftermarket head unit fitted in place of the original · moderate
- Module not coded to the vehicle · specialist
- Corroded or loose connector · easy
- Poor wiring splice in an aftermarket installation · moderate
- Faulty aftermarket alarm or immobiliser installation · moderate
Less common
- Software updated on one module only · specialist
- Damaged data bus wiring · moderate
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
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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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