Rick's Free Auto Repair Advice

Jeep P0456, P0457

Jeep P0456, P0457

Diagnose and fix Jeep P0456, P0457

P0456-EVAP PURGE SYSTEM SMALL LEAK
P0457-LOOSE FUEL CAP

Step by step procedure to diagnose Jeep P0456 trouble codes

Check for leak in purge hose and purge valve

Start by unplugging the evaporative hose from the charcoal canister assembly. Install the smoke machine into that hose. Smoke test the

MOPAR 4891739AA purge valve

MOPAR 4891739AA purge valve

system with the engine off. Check for evidence of smoke along the hose and at the purge valve. If you find smoke in the hose, replace the hose.

If you don’t have a smoke machine, use a handheld vacuum pump and apply vacuum to the hose. With the purge valve closed, this hose should hold vacuum.

If it doesn’t hold vacuum, disconnect the hose at the purge valve and plug it. Then re-test the hose. If it holds vacuum, the hose is good and the problem is the purge valve. Test the purge valve to see if it holds vacuum. Replace the parts as needed.

If not leaks are found or the line holds vacuum, the problem is with the charcoal canister/Evaporative System Integrity Monitor (ESIM). Replace it. This unit has a very high failure rate.

Evaporative System Integrity Module Detector 4861959AC

Evaporative System Integrity Module Detector 4861959AC

Step by step procedure to diagnose Jeep P0457 trouble codes

Remove the gas cap and inspect the gasket for tears or abrasion. Check the filler neck for rust/corrosion. Replace the gas cap

MOPAR 52030377AB gas cap

MOPAR 52030377AB gas cap

NOTE: A P0457 trouble code can’t be reset by the scan tool. Instead, the PCM must complete a drive cycle where it performs a leak test. The gas cap must pass the leak test in order to shut off the light can clear the p0457 trouble code.

P0457 drive cycle: Drive the vehicle for 16-20 miles. Then shut off the vehicle off and park it overnight. If the new gas cap fixes the problem, the gas cap light will shut off on the next key cycle. If the light does not go off, recheck for fault codes.

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Posted on by Rick Muscoplat



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