Intermittent problems are one of the worst to diagnose, even with the best scanner available. If the problem is not present when the vehicle is presented to you, it can be extremely difficult to find the fault. I have heard of workshops keeping vehicles for a number of weeks in an effort to get the problem to occur. Sometimes, the different scenarios never duplicate themselves to reveal the fault.

This 2010 Kia Rio 1.4 petrol had a starting problem that would normally only occur when the vehicle was stopped after a short run, and then a restart was attempted after a few minutes.

The problem had begun a few months back, when the owner had stopped to fill up with petrol and the Kia had refused to start again. By the time the breakdown service had arrived, the engine had fired into life. The Kia gave no further problems over the next couple of days, and the owner had thought this could be a one off.

A reoccurrence of the problem at the next refill, made him consider that this must be something to do with the petrol station he was using, so the third time he needed to fill up he used a different station. The result was the same, and he decided enough was enough and booked the Kia in with me to investigate the problem.

With no codes present and all appearing well, I decided to question the driver further to understand the problem. It turned out he used the Kia to get to work in the morning and then home at night, the only time he tried to start the engine when it was hot, was after refuelling.

Giving the little Rio a good run then turning it off in the workshop, when I attempted to restart the engine, it just spun over without firing. At this point I could read off the code P0323, which indicated that the Crankshaft Position Sensor circuit was intermittent. A new crankshaft sensor solved the problem.

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