VIN code "H"
The engine codes for gasoline engines in the 1985 Chevy Celebrity: 2.5L 4 cylinder engine code R 2.8L V6 mpfi code w 2.8L V6 carburettor code x
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90-9879
You must have an engine scanner to do that.
You have a 1973 nova 350
Diagnostic trouble code
its Chevy 454 Big Block Engine
Wiring, computer, or engine mechanical problem.
Engine cylinder # 5 - misfire detected
Trouble code P0306 means:Cylinder 6 misfire detected
After repairing the cause of the code, you clear the code with a scan tool.
EGR closed position performance.