U0127: Lost Communication With Tyre Pressure Monitor Module
What to do
The car drives normally. What you have lost is the warning that a tyre is going down — so until it is fixed, check your tyre pressures yourself with a gauge, about once a month, when the tyres are cold. The correct pressures are on a sticker in the driver's door frame or inside the fuel filler flap. That takes five minutes and covers the gap completely.
Worth asking which type of system the car has, because it changes the repair. If there are sensors inside the wheels, they contain sealed batteries that last around five to ten years and cannot be replaced separately — so on an older car this can simply be age. If the system works from the wheel speed sensors instead, there are no sensors to fail, and it needs resetting manually every time a tyre is inflated or changed.
In many places a tyre pressure monitoring system that does not work will fail a roadworthiness test on a car required to have one.
What this code means
The tyre pressure monitoring module has stopped being heard from. The general reasoning is at U0100.
Nothing about how the vehicle drives changes. What is lost is the warning that a tyre is going down, and the value of that is entirely in the failure it is designed to catch: a slow puncture that nobody notices until the tyre is destroyed or, worse, until it fails at speed.
Which kind of system a vehicle has decides everything about the repair, and it is worth establishing first.
- Direct systems put a battery-powered sensor inside each wheel, measuring actual pressure. They are accurate, they report real numbers, and the batteries are sealed in and last roughly five to ten years — after which the sensor is replaced whole. A vehicle old enough for this code is often old enough for that to be the real story.
- Indirect systems have no sensors at all. They infer a soft tyre from wheel speed, because a tyre losing pressure has a smaller rolling radius and turns fractionally faster. Cheaper, nothing to go flat, and no absolute pressures — which is why they must be reset manually after inflating or changing a tyre, and why they cannot notice all four going down together.
In the meantime the remedy is free and old-fashioned: check the pressures with a gauge. Monthly, cold, against the placard in the door frame or filler flap. That is what the system automates rather than replaces.
Worth noting that in many jurisdictions a non-functioning tyre pressure monitoring system is a roadworthiness test failure on vehicles required to have one.
Likely causes
Start here
- Corroded or loose connector · easy
- Damaged data bus wiring · moderate
- Failed power or earth supply to the module · moderate
Less common
- Blown fuse or failed supply · easy
- Faulty tyre pressure monitor module · moderate
Symptoms
Components involved
Information, not instruction
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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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