So you have an evap code (p0455, p0442)...
After a year of messing with my evap system, I finally fixed the problem and banished my pesky P0455 code to the 9th circle. I thought I would share my advice to help others that suffer from this problem. Below are the steps I suggest following to solve a P0455/P0442 code.
1. Visually inspect all the hoses running from the gas cap to the gas tank to the evap canisters and then to the engine bay. The evap canisters are on the frame rails and are either cylindrical or rectangular. They are on different sides of the truck depending on the model year. One hose runs from the gas tank to the rear (cylindrical) evap canister. The second hose runs between both evap canisters. The third hose runs from the front evap canister (rectangular) to the engine bay along the frame rail. If a visual inspection reveals no cuts, cracks, or disconnects, move to step two.
2. Replace the gas cap. Disconnect the negative battery terminal (or clear the code if you have a reader/scanner) to reset the computer. Drive a few dozen miles (city and highway) to see if the light goes away. If it does, congratulations! If not, go to step three.
3. Replace the purge solenoid (about $35 at AutoZone). It is located on the passenger side of the engine bay near the headlight. You will see several lines running to it from the frame. It attaches to a small bracket on the body. If this doesn't work, bust out the big guns on step four.
4. Replace the evap canisters. I got mine for around $190 from Rock Auto. Replacing them is easy. They are mounted on a bracket secured to the frame with four bolts (2 on the left, 1 on top, and 1 on the right of the canisters). I used a 1/2 inch ratchet with 3 inch extension to reach the top bolt (which can be a PITA). Leave the canisters mounted to the bracket until you remove the entire bracket. NOTE: Label and disconnect all the hoses going into and out of the canisters before removing them!
5. If these steps don't work, you will probably have to have a shop smoke test your truck. Other evap problems include the fuel tank pressure sensor and the "roll over" sensors on top of the fuel tank.
I hope this helps. My total for a gas cap, purge solenoid, and two canisters was about $260 (labor was free because I did all the work).
2k1 1500 quad,white, 4x4, 5.9.
Exterior Mods: Delta Diamond plate toolbox, 265/75 Firestone Destination A/T, 16x8 American Racing Outlaw IIs, Bilstein HD shocks, debadged, Sport headlights with Silverstar bulbs, front air dam delete, Line-X (OTR, rocker panels and wheel arches).
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