I bought my 2004 bi-fuel cavalier in AZ. I flew out from Medford Ma to pick it up and drive it back. I had the seller add a second (3 gal. equivalent) cng tank. Since owning this issue i will relate has repeated itself 4 times with 4 different machanics.
The check engine light comes on and when it does, the system no longer recognizes that cng is in the tanks - it runs on gasoline only. Each mechanic has found the DTC and it is P1431.
When they erase it, the system goes back to operating correctly and that will last for a varying amount of time - maybe 2 months maybe 2 weeks.
The last mechanic, who says he is a CNG tech, at Liberty Chevrolet in Wakefield said there were no leaks he could detect, he says he traces it back to the fact that there is one sensor on the original tank fill tube but two tanks. But that doesn't make much sense because I can fill both tanks (i fill about 8 GGE, factory original tank is about 5 gge) and use both up and this repeats many times. Then I get this check engine light and P1431.
Any ideas?
The check engine light comes on and when it does, the system no longer recognizes that cng is in the tanks - it runs on gasoline only. Each mechanic has found the DTC and it is P1431.
When they erase it, the system goes back to operating correctly and that will last for a varying amount of time - maybe 2 months maybe 2 weeks.
The last mechanic, who says he is a CNG tech, at Liberty Chevrolet in Wakefield said there were no leaks he could detect, he says he traces it back to the fact that there is one sensor on the original tank fill tube but two tanks. But that doesn't make much sense because I can fill both tanks (i fill about 8 GGE, factory original tank is about 5 gge) and use both up and this repeats many times. Then I get this check engine light and P1431.
Any ideas?
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