Aug 17, 2018 · Variable valve timing solenoid failure due to engine light. If this happens, you must contact your car service provider and have an ASE certified mechanic check it. They can certainly help you diagnose the problem and reset the check engine lights. 2. Dirty Engine Oil. This is one of the variable valve timing solenoid symptoms that are also the cause. The VVT solenoid system performs the best with clean engine oil. Following the leak I had from the VTEC solenoid spool valve assembly which I aimed to repair by replacing the filter on the assembly (catch that DIY here), the leak continued. With the engine running and looking down at the VTEC spool valve assembly, I could just see the oil flowing slowly from the base of the VTEC oil pressure switch to the ...