best way to check for vacuum leak??code p1506


Jul 7, 2008
hey guys yesterday i put A NEW iac valve on my 99 gt and set the tps voltage to .99 it was .96 before i changed it anyway now im getting code
p1506 i cand figure it out i looked for leaks and cant find any visually was wondering if there is a better way please help having alot of trouble since i had my car dyno tuned with the idle and i cant get the guy who tuned it to get me back in he always is busy wich for him is a good thing but not for me just need some help til he can work me in

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propane based vaccum leak detector.

The best way is with a smoke tester. However, this is out of the reach of most home mechanics.

Next best way is with a propane based tester. Vacuum Leak Detector: Automotive

Don't spray carb/choke cleaner (or brake parts cleaner). It may damage gaskets thus making your problem worse.

OBTW, it is a waste of time to set the TPS voltage on a 1996+. The TPS is not used in the same way as before. It is far more important for the TPS signal to be STABLE.

Also, did you alter the throttle body set screw? If so, this could be your problem.

See the following post #3: