Check engine light

I have a 97 F150 with a 4.6L V8 and for the last year I have been having a reoccurring problem with my check engine light. My local mechanic has checked the computer and conferred with the mechanics at the local Ford dealer and followed all of their suggestions, but to no avail. He has replaced the EGR and DPFE valves, the EGR solenoid, has cleaned the EGR intake passage and replaced the rear O2 sensor on the exhaust. Each of these parts were based on the computer information. Each time a part was replaced the light would come on and a different report would come out relating a different area. Now the light is on again and the computer says there is “a low oxygen supply to the EGR”. We are at a loss as to what to do next, and I would like some direction. I bought the truck new in Nov of 96 and my mechanic is the only person to service my truck since then, other than warranty work. Any information would help. This is the only critical problem in almost 12 years of ownership.

One area that can cause an insufficient EGR gas flow code is the orifice located in the EGR exhaust gas supply tube. This orifice can become restricted with carbon. When this happens, not enough backpressure is applied to the EGR valve. And because this is a backpressure induced EGR system, the EGR valve fails to open fully and you get this code. Check the link below and you’ll see where this orifice is located.


dean50, I have just encountered a similar problem. My 1995 Dodge Dakota with 230K miles just turned on the “check engine” light for the first time ever. I had promised my truck a tune up on Friday and bought the plugs, wires and rotar in expectation of my mechanic working on Dakota.Blue on Friday. But then he ended up being to busy so I drove down to Carlsbad (from Redondo Beach) to visit a girl friend and en route the dreaded light came on. So I figure my Dakota is pissed-off at me for not honoring my promise of a tune-up on Friday. Is this of any help? Did you promise your F150 a new set of tires, and then put-off the purchase, right before the light came on? This may sound WAY SILLY, but who knows …

No, she has been pampered. I think it might be a glitch put in by Ford to sell people a new truck every ten years.

Had a crack in the vacuum hose from EVR solenoid to vacuum source. My mechanic found it by blowing low pressure air through the hoses and checking with the vacuum gauge.

This truck, no matter how pampered, is still 11 years old. Funny things start to happen, like vacuum hoses break, seals harden, and leaks start. Unless it’s been done, I’d simply replace every vacuum line. And comb the engine for seal leaks, especially PCV, valve cover, and air intake hoses. Certain leaks, even small ones, can set trouble codes. The biggest problem with EGR and Evap codes are usually with old, brittle, and cracked vacuum lines.