- Dirty or low engine oil
- Valve timing
- Oil control valve
- Variable Valve Timing controller assembly
- Engine Control Module (ECM)

There is a service bulletin for the following Toyota models:

2002 Toyota Camry
2002 Toyota Solara
2001–2002 Toyota Highlander
2001-2002 Toyota RAV4
Toyota Factory Service Bulletin OBDII Code P1349

The P1349 code is triggered when the valve timing does not change from of current valve
timing or the current valve timing is fixed.

- Engine Light ON (or Service Engine Soon Warning Light)

Variable Valve Timing (VVT) system controls the intake valve timing to proper timing in response to driving condition. The Engine Control Module (ECM) controls Oil Control Valve (OCV) to make the intake valve timing properly, and, oil pressure controlled with OCV is supplied to the VVT controller, and then, VVT controller changes relative position between the camshaft and the crankshaft.