A **steady** glow-plug light (the orange coil symbol) on startup is normal — it tells you the plugs are pre-heating. A **flashing** glow-plug light is the diesel equivalent of an engine management light: it means the ECU has logged a fault that needs attention.
Common UK causes
- One or more failed glow plugs (very common over 80,000 miles) - Faulty glow plug relay or control module - Failing diesel injector with poor spray pattern - Camshaft or crankshaft sensor fault - Boost pressure or MAP sensor fault - DPF or EGR codes that the ECU has bundled into the glow-plug warning
What to do right now
Drive gently to a garage within a day or two. The car may go into limp mode at any point — avoid motorways. Get the fault codes scanned (£45–£90) before paying for any guesswork repairs.
Typical UK costs
- 4 new glow plugs fitted: £120–£280 - Glow plug relay: £80–£180 fitted - Snapped glow plug removal: £180–£450 (specialist job) - Diesel injector replacement: £250–£500 each - Crankshaft sensor: £90–£180 fitted
Can I keep driving with the glow plug light flashing? — Short distances at low speed, yes. Don't plan any long trips — limp mode can engage without warning.
Why do glow plugs snap when removed? — Carbon builds up around the plug threads. Many UK garages refuse the job because of the risk — specialists charge £180–£450 per snapped plug to extract.
Bob's Mechanical Repairs — independent family-run garage in Birnam, Dunkeld, Perthshire. Call 01350 727 276 or email bob@bobsmechanicalrepairs.co.uk.