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Discussion Starter · #1 ·
Hi,
Getting into car and driving off I notice Tyre warning light on.
Checked all tyres which looked fine, turned ignition off then on and carried on drivingg to work. 12 miles.
Left work 8 hours later and warning light was still on then after 15 minutes turned off and was fine for a few days.

Now its done it again.

Any ideas all pressure are fine.
 

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Have you used the setup.
 

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The system can trigger the light too soon... because of the lower outside temperatures the measured pressure in tire will drop. There is just a small tolerance.
When sensores are calibrated in a 10-15 deg. garage... The lower outside temperature will make the pressure drop a bit and make the light go on.

My (chief) mechanic have several customers each day because of that.. nothing wrong with tires or pressure. Just because of the different temperatures and small tolerane it makes the light go on in your dash.
 

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mccldd said:
I'm at work with it at the moment with no manual.
Can someone advise how to calibrate it whilst their cold
It seems no so urgent to me but give it a try.
 

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DutCHR said:
The system can trigger the light too soon... because of the lower outside temperatures the measured pressure in tire will drop. There is just a small tolerance.
When sensores are calibrated in a 10-15 deg. garage... The lower outside temperature will make the pressure drop a bit and make the light go on.

My (chief) mechanic have several customers each day because of that.. nothing wrong with tires or pressure. Just because of the different temperatures and small tolerane it makes the light go on in your dash.
What is a small tolerance.

The TPMS must warn the driver if the tension in one or more tires is
20% lower than the correct tire pressure in a tire that is at operating temperature ('hot tire').
If the voltage has reached that lower limit, the system must issue a warning within a maximum of ten minutes.
The system warns anyway if the tire pressure is lower than 1.5 bar.
The TPMS must at least operate from a speed of 40 km / h up to the maximum speed of the car in question.
 

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The ambient temperature can make a significant difference to tyre pressure.

For example, if you inflated the tyres to the recommended pressure (2.2 bar/32 PSI from memory) in ambient temperatures of 10c, at 0c the pressure will be 2.1 bar/30 PSI, and at -5 will be 2.0 bar/29 PSI. Perhaps that is a big enough difference to trigger the warning light?

This is based on a cold-tyre inflation after the car hasn't been driven for at least two hours. Driving to the local garage will affect the pressure difference more because the tyres will hold some heat.
 
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