Northstar Engines and System Technical Discussion Discussion, 2001 dts p0420 in Cadillac Engine Technical Discussion; I just bought a 2001 DTS and when I took it WOT the first few times my friend, who was ...
I just bought a 2001 DTS and when I took it WOT the first few times my friend, who was tailing me, told me that there was black smoke coming out of the exhaust when I punched the gas. After checking the codes and seeing P0420 and C0662 (Current), I hoped it was a bad FPR pushing a rich fuel mix.; while also hoping it wasn't the Catalytic Converter. I changed out the FPR and the engine runs just fine and no more black smoke, from what I can see; but, while idling every once in awhile the "Service Engine Soon" light will illuminate and the idle will become shaky. I will run the codes and P0420 (C) comes back but as soon as I clear the codes, the idle is completely normal. Any thoughts?
P.S. Before changing the FPR I was getting an average of 11mpg (city) in 90 miles; after I am getting 19mpg (city) in 40 miles.
In addition; the "Service Stability System" message comes up a lot along with ABS C1214 C1248 and C1295; usually they read as history, but occasionally they read as current. I read that this could just be a faulty EBCM module ($150 to fix).
Automobile(s): White Diamond '03 DHS (with DTS floor shift)
Re: 2001 dts p0420
You check the FPR by pulling the vacuum hose at idle. If fuel leaks from it, it's bad. If not, it's good. If your mileage improved, I'd suspect it was leaking and adding to the carbon in the chamber and exhaust (running rich).
The black smoke you saw was likely carbon being cleaned out of the combustion chamber and exhaust system.