How to diagnose vvt issues on Lexus 4 liter V8


New Member

My 1998 LS 400 (177k miles) intermittently gives me these codes and turns off the VSC:
P1346 (Variable Valve Timing Sensor Bank 1 Range/Performance Problem)
P1351 (Variable Valve Timing Sensor Range/Performance Problem Bank 2)
P1346 P
P1351 P

On the possibility that the problem is the sensors or actuators being clogged with dirty oil, my mechanic did a hot oil engine clean, then I put 1/2 can of Seafoam into the engine oil.

After I reset/clear the codes with a code reader, the car works fine for anywhere from 5 miles to 20 miles, then the check engine light comes on again and the VSC turns off.

Any advice on how to diagnose this, to determine if it's just the sensors or if it's a deeper problem?


Well-Known Member
Has any other repairs or maintenance been done on the engine recently? Have you resistance checked the sensors and solenoids? I also remove the solenoids and manually power them up.