P0300 Chevrolet -

Question

I have recently had my intake gasket replaced, but after I picked the vehicle up I noticed the transmission shifted a little rough for the first couple of uses, but then seemed ok for a few days and then the engine light came on and my transmission wouldn't shift into gear at 40 mph. instead my rpms would go up and the vehicle would slow down. I have replaced an oxygen sensor, rotor, cap, plug wires, and plugs since then and could not find any noticeable leaks around the intake. I was told that a faulty coil or fuel injection problem could be the cause as well and throwing off the computer with the correct air/fuel mixture which is preventing the transmission from shifting at the correct time. Thoughts? Suggestions?

Answer 1

P0453 might be a bad Fuel Tank Pressure Sensor, it might also be causing the P0300 

 

Possible causes

 

- Faulty Fuel Tank Pressure Sensor

- Fuel Tank Pressure Sensor harness is open or shorted

- Fuel Tank Pressure Sensor circuit poor electrical connection

 

https://www.autocodes.com/p0453_chevrolet.html