Q When the airbag warning is lit, is it an easy fix?

I recently fired up the engine of my 2018 Fiat Ducato as it had not run for the previous month. All was well.

When I fired it up again, a few days later, the airbag warning light stayed on with the message ‘check handbook’. As I was going on a rally I decided to leave it but the light remained on. The handbook says visit a Fiat dealer. Can I cure this myself or should I visit a dealer?

David Wright

A Airbag warning lights are a pain. They can be caused by any fault, however temporary, originated by any device connected to the airbag control unit. These naturally include airbags, but also seatbelt pretensioners and seat occupation sensors.

Something as simple as moving the driver’s seat back or forward can disturb the wiring connections; and this is the most common cause of a warning light of this nature on any vehicle so equipped.

The airbag control module is a particularly troublesome item with the Fiat Ducato as it seems to be particularly sensitive to moisture, and this is more frequently found in motorhomes than in commercial vans.

The first thing to do would be to rule out anything completely obvious, so check for coolant leaks into the cab. If the matrix inside the heater unit is going to leak, it will deposit coolant straight on to the airbag unit, which is located behind the lower dash in the middle of the cab floor. If your coolant seems low and there is evidence of leaking on the floor, this will need to be sorted out.

Check under the seats for anything that has been stowed away and has come into contract with the wiring for the seatbelt pretensioners and sensors.

In most cases, though, getting the vehicle plugged into a diagnostic system that can read codes from the airbag system will provide at least clues as to what is wrong. You may see a particular device named and, initially, the wiring to that device would need to be checked before assuming that the device is faulty. They are often not.

If, on the other hand, the diagnostic unit cannot communicate with the control unit or it does but describes internal faults, then it will need to be repaired or replaced.

There are people out there advertising their ability to repair airbag control units, but the costs may end up being very similar to that of purchasing a new one and having it installed and programmed by a Fiat workshop. It will come with a warranty, too.

Anyway... let’s not worry about that yet. It may be a simple fix. Get it plugged in and see what you can learn about what is going on.

David wrote back to say that he had some difficulty with his local garage, which was under the impression that it needed an Iveco-specific diagnostic tool to read the codes. This is not true.

Apart from the obvious Fiat Examiner tool, I used a MultiECUScan device to get into all of the Fiat systems.

There are also generic tools made by Autel, Reflex, Texa and MaxiSYS on top of the widely used units from Snap-on and others that will work. In my experience only the MultiECUScan comes close to the functionality of the Fiat OE kit, but the others should be able to get to where you need to be for airbags.

Nick Fisher