Car Clinic: What caused warning lights when using a space-saver spare wheel?

Q. When I used a space-saver spare wheel on my Citroën DS4, warning lights started flashing, then the electronic handbrake applied itself. Why?

GG, Co Tyrone, Northern Ireland

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A. The DS4 has a tyre-pressure monitoring system (TPMS) fitted to each wheel and a warning flashes if the pressure drops. The flat tyre was in the boot, reporting that there was no pressure, hence the warning. The sensor also measures wheel speed and because the wheel was stationary this triggered another warning.

Once you have a new tyre fitted you can reset the TPMS ­— your handbook will have the details. The handbrake should never apply itself, though. If you are convinced this happened, you should stop driving the car and immediately consult your dealer.

INSPECTOR GADGET
Dave Pollard has written several Haynes manuals and has tested just about every car-related accessory — read more from Dave here.

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