Re: Sable Vacuum leak, P430
If there is an exhaust leak before or through an O2 Sensor, this code can set. Also, a bad downstream O2 sensor can cause this. But you have two upstreams abd two downstreams on your car. If you had a scan tool with a full data display you could watch the upstream and downstream O2 sensors work. You should see the upstreams switching continuosly and the downstreams switching rarely. If the downstreams are switching the same amount as the upstreams you either have a bad O2 sensor or the cat is bad. Try the downstream O2 sensor first. If they still switch the wrong way then you have a bad cat. If the switch the right way then you're all set. Are you sure its a vacuum leak??? If it has a plugged up cat it will cause a loud hiss similar to a vacuum leak and the car will run poorly or stall. This is from the excessive backpressure.
Master ASE Certified L1 Chrysler Technician- still a Ford fan at heart.
1964 Thunderbird Hardtop- Chantily Beige- 390 FE 4V V8-Uncle's Car
1966 Thunderbird Convertible- Red- 390 FE 4V V8- Uncle's other car- waiting for paint and body work!!!