Ask a Mechanic Online and Get Answers to Your Car Questions
Thank you very much for your question.
The glow plug warning light will flash or illuminate when the engine management unit (ECU) detects a fault. This fault will have been stored in the ECU's memory and can be retrieved using a suitable code reader. When the light is on or flashing, the engine may be put into a safety mode to prevent any possible damage occurring, if this happens, you might feel a drop in performance.
You will need to have a diagnostic check carried out to determine exactly what the fault is.
Most garages are equipped to carry out this check nowadays, so I would suggest phoning around for a quote unless you use a garage regularly. You do not have to go to a main dealer. The most common faults are faulty cam or crank sensors, but many other things can cause the light to flash, so guessing isn't really a viable option and will certainly cost you money.
Continuing to drive your car should not be a problem if you take it easy. However my recommendation would be to have a diagnostic check carried out as soon as possible, just in case.
I hope this answers your question.