Symptoms drivers describe
- Long cranking before it fires from cold
- Starting normally once warm
- White or grey smoke on the first start
- Rough idle for the first minute
Possible causes
- A battery weak under cold load
- Failed glow plugs or a faulty relay on diesels
- Fuel pressure loss overnight from injectors or a pump
- Low compression on one or more cylinders
- Faulty temperature sensor giving the wrong start enrichment
- Ignition components on petrol engines
What you can do
- Note the temperature and how long it cranks
- Mention whether it improves after a longer run
- Avoid long cranking bursts, which strain the starter and battery
How we check it in the workshop
We test battery and cranking voltage, check glow plug circuits, measure fuel pressure hold-off and carry out compression testing where indicated.
Is it safe to keep driving?
Not dangerous, but it usually worsens as the weather cools and can leave you stranded.