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P0455 OBD2 Code on 2001 Dodge Caravan: Diagnosis and Resolution

Model: 2001 Caravan Fault Code: P0455 Posted: 2012-10-12 17:13

I recently encountered the P0455 diagnostic trouble code on my 2001 Dodge Caravan, and I wanted to share a detailed troubleshooting process that may help others facing similar issues. The check engine light remained on for some time without any noticeable symptoms like fuel smell or performance problems. Due to cost constraints—smoke testing costs $90 and dealer diagnostics run $100—I avoided professional services initially. Instead, I performed an OBD2 scan using a 'key dance' method, which revealed both P0442 and P0455 codes. I visually inspected all evaporative (EVAP) system hoses and found no visible cracks or damage. To simulate a smoke test at home, I built a simple DIY smoke tester and discovered a cracked fuel filler neck. After replacing the fuel filler, I reset the OBD2 system and drove approximately 50 miles—only to find the check engine light reactivated. A second smoke test revealed a leak near a black plastic component (likely an EVAP vent valve) attached to the EGR valve. I replaced both components as they were sold together. After resmoking, no leaks were detected. The system was reset and I drove 38 miles before the P045 or code reappeared. Despite multiple smoke tests showing no visible leaks, the P0455 code persists. However, the vehicle runs smoothly with no fuel odor. A key test I performed involved filling the tank to capacity and resetting the system after a long drive (over 50 miles). The code did not return, and the check engine light stayed off. But here's the odd behavior: if the gas cap is removed and resecured before starting, the vehicle starts normally. If only loosened without being fully re-tightened, it fails to start—acting as though the fuel tank is empty. This suggests a potential issue with the fuel cap or its sealing mechanism. So, my question: could this be a faulty or defective Leak Detection Pump (LDP) causing the P0455 code? Or is there another EVAP system component at fault? I'm seeking input from experienced mechanics and forum members on this specific 2001 Caravan case with persistent P0455, especially regarding the behavior of the fuel cap and starting issues.

Related fault codes
P0455
Comments (3)
Anonymous 2012-10-12 19:36

While possible, I've never seen a Leak Detection Pump (LDP) fail in this specific way. The symptoms point more toward a blocked vent line, a crossed EVAP hose connection, or a restricted return fuel line instead.

Anonymous 2012-10-13 00:33

This clearly points to an evaporative emissions system issue. I recommend checking for a damaged fuel cap, possible tank impact damage, or a warped/bent filler neck. Also inspect all EVAP hoses for leaks. I've heard reports of leaking gaskets on the fuel tank sending unit causing similar symptoms. Don't overlook the carbon canister—check for cracks or water intrusion. There's also an EVAP pressure sensor in the system that should be tested. The fact that the vehicle won't start without reapplying the cap is a strong indicator that the gas cap or its sealing mechanism may be faulty.

Anonymous 2012-10-13 10:01

Possible causes include a malfunctioning vent valve, improper hose routing, or an OEM-grade fuel cap with degraded seals. These components are common points of failure in older Caravan models and should be thoroughly evaluated when diagnosing P0455.