Got my Sunpro scanner, works great. However I have 3 error codes and not sure how to fix what is wrong.

420-Catalyst system effeciency below threshold9Bank 1)
171-System adaptive fuel too lean (Bank 1)
174-System adaptive fuel too lean (Bank 2)

I figure that 420 is related to 171. But why would I be getting these? Do I need to have injectors cleaned? The fuel filter was recently replaced. Or could it have something to do with the K&N filter I may have overoiled last fall? Or are there sensors that need replaced? I can do any mechanical work required but am not really knowledgable about the inner workings of an engine. I would appreciate any help that anyone can give me, especially any of you Ford mechanics out there.

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97 F-150 S/C 4x4 ORP XLT 4.6 K&N , Flowmaster w/dual tailpipes, Bosch+4 plugs,Ford 9mm wires,Superchip.Patriot fiberglass toneau cover, Westin chrome step bars. Rear seat lift 4".
Kenwood 4011 stereo, USAcoustics 2150 amp, Profile electronic 3 way crossover, 2 10" IDQ DVC's.

FUTURE STEREO MODS:
Memphis components in front, Pioneer 3ways in rear, amp for the components, and a cd changer.

FUTURE PERFORMANCE MODS:
4.10 gears, Edlebrock shocks, supercharger, Airaid, power pulleys.

OTHER FUTURE MODS:
Ram Air hood w/functional ram air, suspension lift, 16.5" polished wheels, 35" tires, and sunroof.

 

Had plug wire back off on my 97 f-150 today and it put the check engine light on. After I fixed the problem the light would not go off. I think this is something a Ford dealer is suppose to do.
When I got home, I did the unplug the battery trick and that did it (you will have to leave it off for about 30 mins.). The engine light went off and the truck is running fine. My advice to you is to try this and see if it fixes your problem. Could be there was a small problem that fixed itself (over oiled filter) and now needs the reset. Try it and if it continues, then see the dealer.

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Black 1997 F-150 Supercab Flairside. 4.6L with Jocobs DIS, K&N Generation II, Cat back Exhaust (nice rumble). 17" Off Road wheel pkg. Lots of body mods. 4 yrs old and still turns heads...

 

Here's my $0.02 - Just some guesses.

The Bank 1 and Bank 2 are referring to the same problem, just each side of the engine.

A low restriction air filter will cause an engine to run slightly leaner, and an over-oiled air filter would cause it to run slightly richer. Your exhaust mods might also cause the engine to run slightly leaner, and your sensor's are detecting that you are outside of the normal parameters.

The engine might be completely healthy, just outside what the sensors are told to expect for a stock configuration. I think this is more likely than the over-oiled filter causing damage.

Another possibility - changing from the over-oiled filter to the properly oiled K&N resulted in enough of a change in intake tract restricton to trigger a code.

Good luck sorting it out - but if the engine runs healthy and the spark plugs look normal (not grey or white which would indicate too lean or hot) I wouldn't worry too much.

 

I forgot to mention my check engine light has been on since I bought it used. It was out of warranty and it ran fine so I wasn't worried about it. I've done the battery thing many, many times doesn't work for my truck. I will look at the plugs and see how they look. I reset the codes last night so if they come back on I'll see which ones come back if any. The truck had seemed to have lost a little power lately so I thought it might attributed to the check engine light which is why I bought the scanner.

 

Just guessing: Possibly a bad throttle position sensor causing drops in fuel pressure in the fuel rails. Course it could be the gas cap. Try that first.

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2000 F-250 Super Duty, SuperCab XLT, Oxford white with medium grey cloth captains chairs, 5.4L Triton V8 (260 HP version!), 4R100 4 Speed Automatic Transmission, 4 wheel ABS, Deluxe Aluminum Wheels, Trailer Towing Package, Class IV Hitch, Reece load distribution system, Escort Sensor II Electronic Brake controller, K&N filter, Sure Stop towing skirt, "Westin" black powder coated step bars, "White-White" head lamps, Herculiner bed liner, ISSPRO Tranny Temp Guage, Excursion center console.

 

Sounds like your running too lean overall and the computer can't compensate for it. Try checking your fuel filter, should be changed every 30K. Hook up a vacuum gauge, and check vacuum at idle, should be 20 to 21", a minor vacuum leak would cause a lean condition. If the truck has over 50K miles, it could be time for new O2 sensors, they don't last forever. Check the pressure on the fuel rail, and make sure that it varies with the engine vacuum. I don't know what the spec is but typically its 30 to 50 psi. Hope this helps

 

Just a shot in the dark, but don't most scanners come with a decoding book? Or does this one have a little screen and tell you the DTC's?
Anyway it sounds like an O2 sensor or a convertor problem.

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stock 98 XL, Reg. cab,4.6, Auto, HD cooling package, 255/70R16 on styled steel wheels,3.55LS, Black with chrome grille and bumpers! MODS: custom stereo by me, building speaker box was a !@#$%. K&N air filter w/ airbox mod, a complete keyless entry system.

 

Well, the 420 code came back today. I'm guessing it must have something to do with the Flowmaster. Anyone else with a Flowmaster cat-back system having check engine lights?