Michael McAleer answers your queries
From Dermot Pearse:
I read with interest the article in Motors (May 4th) about the lifespan of airbags. It was never mentioned to me at any stage that I might need to get them replaced or that they even run out in time.
Is it not part of the warranty that these are replaced by the manufacturer, given that they are a vital part of the safety equipment? How can I check them?
Airbags generally have a lifespan of about 10 years - longer in some new cars these days. They are not part of the warranty as a manufacturer will not cover parts like this, but it is something that we should pressure car companies to do. After all, it's not as if airbags deteriorate through wear and tear.
Testing an airbag, however, is a bit of a catch 22.
The problem is that there's no real way of testing it unless you deploy it, in which case you end up covered in talcum powder and none the wiser as it's a one-off event.
Ultimately, it's worth remembering that an airbag is a secondary safety device and is not meant to be a first line of defence. The most important thing that will save your life is a seatbelt.
From James Phelan:
The electrics in my car keep going flat, even though the battery is fairly new. I have double checked on numerous occasions that I am not leaving any switches on, or the radio/CD unit still playing, when I lock the car. Have you any ideas what's causing this problem?
In all probability this is an earthing problem from one of the in-car accessories such as the stero system, cigarette lighter, possibly even a faulty boot light which is on even when the boot is shut. It is a fairly common complaint, but one that can be sorted out relatively quickly and painlessly.
The best thing to do is to connect a multimeter to the battery to check the exact current being drawn when the engine is not running and all functions are switched off.
The reading at this stage should be almost zero, but if it is significant then pull out each fuse in turn and then reconnect them, watching the meter reading closely.
If it suddenly drops to approaching a nil reading when the fuse breaks the circuit, then you have identified the system with the fault and the source of the current drain.
From Mark Murphy:
I've done about 65,000 miles in my current car from new, and recently it has started to run roughly and occasionally stalls. I took it to a garage and they say it needs a new lambda sensor.
Can you please tell me what this is, and why it could have such a dramatic effect on the running of the car?
The lambda sensor is a vital part of a car's engine management system, and acts to feed back information on exhaust gases to the ECU to help ensure the correct petrol to air ratio is maintained at all times.
Some manufacturers recommend that the sensor be checked every 18,000 miles or two years as a faulty unit can lead to increased exhaust fumes and, more crucially for your pocket, much poorer fuel consumption.
Lambda sensors are meant to last for 60,000 miles but unfavourable conditions may shorten their life.
They are constantly exposed to extremes of heat and chemicals, and such things as contaminated or leaded fuel. Oil or water in the combustion chamber will shorten their life span considerably.
Send your queries to Motors Help Desk, The Irish Times, Fleet Street, Dublin 2 - or e-mail them to motorshelp@irish-times.ie