One of my family members owns a Ford Econoline E150 modified with a roof extender and power wheelchair lift, however the engine is a stock V8 which runs on regular gas.

Anyway, after a fairly long road trip (300 miles total) the check engine light comes on and the car has a P0104 trouble code. Although googling tuns up pages saying it's the MAF or a leak in the intake, our MAF sensor is fine but there are signs of EGR trouble.

So my question is, what could be causing this EGR problem, and also, whether having a roof extender and power wheelchair lift would require we treat the car as a commercial vehicle/truck rather than consumer car since there's a bit more load on the car.

Also, the car is only at around 23,000 miles, however it is a 2002 Econoline, so I doubt this is due to the engine being worn down.

  • have you tried changing the air filter? See this
    – Tester101
    Aug 23, 2011 at 15:37

2 Answers 2


Speaking only in generalities (not being familiar with Fords of any kind), EGR systems fall victim to damaged vacuum lines occasionally, so check those. They can also clog up with carbon enough to fail to operate properly. Neither would normally happen in so few miles, but if the load was heavy enough, I suppose the enrichment program might lead to the second issue. How's your gas mileage?

  • Thanks very much for the answer. Turns out that using Seafoam to clean the intake did the job of fixing the code. In terms of mileage, I think the car gets 15mpg hwy (it's a huge car, carrying a huge load) but since the cleaning I'll be checking to see if there's any improvement. The brake line however burst soon after the change (from wear) so I"m not sure if the loss of pressure in that system also caused the trigger. Either way, the code is clear, so the suggestion helped a lot.
    – theonlylos
    Aug 23, 2011 at 19:15

Symptoms for a bad EGR valve and a bad MAF sensor aren't too different, it is a fair possibility that the MAF needs to be cleaned (easy to do).

Just take the MAF sensor out, clean the electrical connection and spray through the sensor with some MAF cleaner or (though it's harsher it does work) Carb cleaner. Inspect the element, it should be a small silver filament, similar to what you'd see in a light bulb or an older space heater. Once that's taken care of put a bit of Dielectric grease on the electrical connection and give it a shot.

Similarly, the MAF sensor could be failing due to having a clogged air filter. Pop the filter out and take a look, if it's dirty (a vehicle that old with low mileage may not have received adequate air filter replacements) just simply replace it and if possible either wipe out the air box with a damp rag or spray it out with compressed air to remove some of the dust sitting in there.

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