An illuminated Check Engine Light could indicate that one or more of the ignition coils has failed due to excessive spark plug gap. To fix this problem, the ignition coils that have failed, the spark plugs, and all coil boots should be replaced.
Problems for specific Ford F-150 years:
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Most reported 2004 Ford F-150 problems
Our technicians tell us the spark plugs in this engine can be very difficult to remove. Ford has issued a service bulletin (08-7-6) to address this issue, which includes a recommended procedure on how to remove the plugs. Failure to follow the recommended procedure can result in the one or more spark plugs breaking off in the cylinder head.
The recommend procedure is as follows. Using this procedure will greatly reduce the chance of breaking a spark plug.
1. Break the spark plugs loose when the engine is warm.
2. Turn each plug 1/8 to 1/4 turn and soak the treads with 1/2 to 3/4 teaspoon of Motorcraft Carburetor Tune-Up Cleaner or a quality penetrating oil. Do not try to remove the plugs at this time.
3. Let the threads soak for at least 15 minutes.
4. After the soak period, tighten and loosen each spark plug, working it back and forth until the turning effort is reduced. Then, you can remove the spark plug.
There are special tools available to remove the broken spark plugs and repair shops will often charge additional labor time, over and above the quoted spark plug replacement cost, for the removal of each broken spark plug.
Water leaks that appear at the headliner and rear seat area have been known to be coming from the rear high mount stop light. The gasket that seals the light becomes warped over time and allows water to enter through the stop light into the cab area. A revised stop light is available, but I have found that properly placed caulk or foam tape will work also.
Intermittent rough idle may be caused by the EGR sensor sticking, causing the EGR valve to stay slightly open. Our technicians tell us the valve and sensor must be replaced together to correct this concern.
Check engine light with PO 171-174 codes with the 5.4 motor.
PCV elbow is leaking vacuum at the connection at the back of the throttle body by the firewall.
The vacuum elbow has to be replaced and is available from Ford either with the entire PCV line or just the elbow.
make sure you remove the battery cable for 30 seconds after the repair to clear the adaptive memories.