Code P0442....The PCM has detected...... - F150online Forums



Code P0442....The PCM has detected......

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Old 08-16-2006, 07:36 AM
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Code P0442....The PCM has detected......

A small leak in the evaporative emissions control system.....


Vacuum leak maybe??? Just changed some vac lines, and tee connectors that looked suspicious....Any other ideas guys....Thanks....
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Old 08-16-2006, 09:27 AM
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P0442

The computer commands that a vacuum be pulled in the fuel tank, then measures the negative pressure in the tank to be sure that the vacuum is present, is correct, and that it holds. In the case of a large leak, it cannot pull a vacuum so the PCM sets the P0455 code. If the leak is smaller, it sets the P0442 code. Newer vehicles have an even tighter test for smaller leaks (P0456). It also means that the test has failed on two consecutive test cycles.

The fuel cap is the only thing that a typical owner can access. Check to make certain it's tight and that its seals are clean and intact.

If this was the result of a state-mandated emissions check, they should have also tested your gas cap. If not, you can try swapping it.

If you determine that the problem is not the gas cap, your best recommendation to locate the repair is to hire a shop (probably the dealer) that has a smoke generator to locate the leak. Likely fault locations are the CV solenoid, canister, fuel tank filler grommet, one of the seals on the top of the tank, one of the many hoses in the system, the purge valve, or an electrical fault with the pressure sensor or one of the solenoids.

Steve
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Old 08-16-2006, 09:15 PM
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Thanks.... I actually did find a small crack, about a 1/2 in long, and a hair wide in the filler neck right under the gas cap....So i put a dab of sliicone on my finger and filled it in....Maybe tomorrow, I will buy a new cap too....Do I need to get the code reset, or will the processor re-test, and reset the light if the leak is fixed...
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Old 08-16-2006, 10:06 PM
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If you do nothing and the fault is corrected, the PCM will, in its own sweet time, turn off the CEL.

If you want to reset it yourself sans scanner, open your hood, locate the small fusebox near the corner of the firewall and the driver's side fender, open it, and remove fuse F1 for 10-15 minutes while the ignition switch is OFF. Reinstall everything and the computer's KAM should be reset.

Steve
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