Toyota Repair: 2000 Toyota Celica GT, toyota celica gt, air fuel mixture

Question
Codes P1693 and P0171. What do these mean?

Answer
The first code indicates a problem with the oil control valve(OCV)for the variable valve timing(VVT)system, this valve controls oil pressure to the variable cam timing system and the best way to check it is to connect a scantool to perform a test of the valve using the active test method, the toyota dealer can do this. The second code may be directly related to the first malfunction, it's a lean air/fuel mixture which could be caused by the first code.