^^Does this means it is intermittent?

Could just be a loose connection somewhere if it is? I had a similar problem when the light came on when I braked and came to a stop, but as soon as I accelerated away it went off. It turned out the there was a loose wire that was moving about on the AIT sensor connector which made contact when weight transferred rearward (acceleration), and lost contact when weight transferred forward (braking).

When you have the ignition on (engine not running) is there a flashing fault code on the engine trouble light? If not (because it's not currently showing the fault) then you should be able to find out the fault code using a diagnostic tool.

Did the people who did the service read the historic fault codes stored in the ECU to get some idea of which sensor is causing the issue?

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