An intermittent warning light and ticking noise from the engine.

The customer repeatedly described the warning as the oil-pressure light. The workshop could not reproduce an oil-pressure warning during testing, but did find an engine warning light, an exhaust VVT code and a ticking noise through the valve cover.

An oil-pressure switch, fuel injectors, spark plugs, oil and filter had already been replaced during the investigation, but the warning kept returning. An initial oil-analysis result suggesting fuel dilution was later found to be unreliable. The customer eventually pointed out the actual light: it was the engine warning light.