P0455 OBD2 Code Explanation and Troubleshooting for 1997 Jeep Grand Cherokee
I own a 1997 Jeep Grand Cherokee, and the check engine light has activated. The diagnostic trouble code P0455 indicates a large evaporative emission system leak, possibly originating from a loose gas cap, evaporation canister, or vacuum line issue. I have already replaced both the aftermarket and original Jeep-brand gas caps, as well as the purge solenoid. Additionally, the vehicle's vacuum system was smoke-tested twice with no positive results. Despite these efforts, the check engine light reactivates approximately every three days after being reset. The most recent repair involved replacing a vacuum line nipple by a mechanic, which resulted in the light staying off for 2.5 weeks. However, upon today’s scan using an OBD2 tool, the system still reports a significant evaporative emission leak (P045-5). What other potential sources could be responsible for this persistent P0455 code?
Possible causes include fuel pump seal failure, filler neck leaks, or cracks in the fuel tank. These are common sources of evaporative emission system leaks in older Jeep Grand Cherokee models and should be considered during diagnosis.