Why your engine shakes at idle
A car that shudders at a standstill but smooths out once you are moving is almost always losing combustion in one or more cylinders, or being fed…
What is your car doing?
Start from the symptom rather than the code. Each guide explains what the behaviour usually means, whether it is safe to keep driving, the live data that separates the likely causes, and the trouble codes that go with it.
It cranks, but it will not fire
The starter turns the engine over normally and nothing catches. That narrows things down quickly: the engine is being denied spark, fuel, or the…
Your fuel economy fell off a cliff
A gradual decline over years is wear. A step change over one or two tanks is a fault, and it is usually one of a small number of things: the…
Something is rattling underneath
Most under-car rattles are cheap to fix and loud out of proportion to their seriousness. A small number are not. The sound, and when it happens,…
The light came on right after you filled up
A check engine light that appears within a drive or two of refuelling points almost exclusively at the evaporative emissions system — the sealed…
It hesitates when you ask for power
A flat spot, stumble or brief hole when you open the throttle means the engine is not getting the air, fuel or spark it needs at the moment demand…
It failed the emissions test
There are two quite different ways to fail: the car emitted too much, or the car could not prove it was testing itself. The second is far more…
It stalls when you come to a stop
Stalling as you lift off and the revs drop to idle means the engine cannot sustain itself at its lowest operating point. The idle control…
The temperature is not where it should be
Both directions are faults, and they are not equally urgent. Running too cold costs fuel and will eventually fail an emissions test. Running too…
Several warning lights came on together
When unrelated systems misbehave simultaneously — ABS, airbag, engine, transmission — the usual cause is not several simultaneous failures. It is…