I've been advised by my local Ford dealer that my O2 sensors should be changed at about 60,000 miles, regardless of whether the "check engine" light is on or off. Replacing these new sensors should result in increased fuel mileage. But only the pre-cat sensors, not the post-cat units. Has anyone done this replacement, and does it help mileage any? Like everyone else, I'm looking for better fuel mileage. 1997F150, extended cab, 4X4, 4.6L, 77,000 miles.

 

If you replace the sensors yourself that's $200 bucks (Canadian for 2). My dealer replaced one spark plug and wire for $330 so do the work yourself!

If you haven't done so I would replace the spark plugs and check/replace your ignition wires. I'm looking at doing that in a month or so and have 42,000 miles now. If one plug went bad I'm sure the others aren't that happy either.

Clean your MAF wire with windex on a Q-tip. Be careful. Put a K&N filter in. Aside from the lower intake air resistance no more filters go in the dump. Better for the environment.

My dealer said it's not uncommon for O2 sensors to go even way before warrantee.

Personally unless the check engine light comes on or it runs worse don't touch the sensors.

Do yourself a favour and get yourself an OBD-II code reader. I could have saved $100 bucks on that one dealer visit alone. It's so precise it even tells you which cylinder is experiencing the misfire = plug or wire bad. You'll also need it to diagnose which O2 sensor is bad when they go (if they go).

 

Thanks IanN and p-ferlow for the replies. I did change the plugs about 10k ago and the wires about 20k. Actually this is the third set of plugs. I tried Autolites platinum's at about 40k and ran them to 66k. Then I tried Bosch platinum. they lasted 2 days before I yanked them out and put new Autolites back in. I have a K&N GenII filtercharger in now along with a cat-back system topped off with a Flowmaster. So air flow is what I would call optimal. I also just had a full fuel and air systsm cleaning done by my Ford dealer. I will clean the MAF unit to be thorough. O2 sensors will cost about $60.00 each(Bosch) so that will probably be my next step. I do most all my own work to keep down expenses. I will look into an OBDII tester. Perhaps a Superchip is on the horizon in the near future. Big expense between the chip and the higher priced premium fuel, but that may become unavoidable to get what I want out of this engine. I love the truck, but just feel that I'm giving up too much power in the bottom end of the rpm scale. It always feels like the timing is slow and I know this is due to the slow advance curve of the stock ignition. Gotta keep those fed's happy.Guess I'll keep testing til I get the Combo I'm looking for. Thanks again for the advise.

 

OBDII tester
What exactly are these what do they do?

And how much does one cost?

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97 F150 Longbed V8 4.6
K&N air filter
K&N FIPK tech MOD & removed elbow silencer
Tires: Yokohama 265/75/16 Geolander AT+
Hyper white xenon bulbs
Bedliner and raven shell
6 disc cd changer
Oil & filter used

Gasoline used

My Truck

 

aablackhawk: i have a 97 f150 4.6L auto trans with 118,000 miles on it. a couple of weeks ago i changed both(pre-cat) o2 sensors myself. bosch's were $50/ea. at advance auto parts. no you do not need a special socket--yes they'll sell you one but i changed mine with just the proper size(i forget) box-end wrench. spray wd40 or such into threaded area to free up the threads and, of course, disconnect the plug at the end of the sensor so you can place wrench around sensor. on the drivers side sensor i had to unbolt a control cable bracket(two bolts--right in front of your face) to get room for my hand to get the plug free. btw, look at the new sensor's plug carefully so you will know what to pull on to get it free. pass. side o2 was fairly easy once i removed the plastic inner fender wall/cover. the bad news is: no improvement in mpg and these were the original o2s--the old ones looked clean with a light gray coloring. a chip will satisfy your longing for a peppier truck.

 

Everything I have read indicates that they go bad at about 60,000 miles tops. They start to read abnormally which prevents the computer from adjusting the A/F ratio properly. This is why the dealer says only the fronts.

If you have emission testing, changing them will help the truck pass.

I have an Integra with 120,000 miles and the sensor has never been changed, but I am probably going to do it this year.

They are expensive and a PITA to change (just like any exhaust component, they will be siezed solid and you need a special socket), so I would call a few independent shops to get quotes on the work. Any parts store can get the sensors, so call around.

Ian

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99 Expedition EB
5.4l, 4x4, 4.10 LS
WMS Tube, Bassani Cat Back Exhaust, Superchip Flipchip, PIAA Superwhites

 

moose-man,
To make it short, the O2c sensor is located in the exhaust system and reads the exhaust gases from the engine. In turn, the sensor signals the ob-board computer of the exhaust gas mixture so it can adjust the incoming air-fuel mixture for the optimal ratio. If the O2 sensor is off the incoming air-fuel charge will be wrong, and consequently the exhaust emission levels will be unacceptable. That's a quick overview of what an O2 sensor does.

 

dbunch5:

I ment the ODB-II sensor reader... not the o2 sensor.. im fully aware of what an o2 sensor is and does but thanks!

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97 F150 Longbed V8 4.6
K&N air filter
K&N FIPK tech MOD & removed elbow silencer
Tires: Yokohama 265/75/16 Geolander AT+
Hyper white xenon bulbs
Bedliner and raven shell
6 disc cd changer
Oil & filter used

Gasoline used

My Truck

 

My check engine light came on at about 46k miles. Dealer checked it out and about $350 smackers later I had two new O2 sensors. Another dealer rip off - should have done myself.

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1998 Expedition EB
- 4x4
- LLS (4 corner)
- Premium MACH Sound System w/6-CD changer
MODS
None yet (But I wanna be like you guys)
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how much are these? will they only read information when the check engine light is on? Is it plain for a novice like me to read, or is it in mechanic speak and codes?At $60 a reading it sounds like a good deal. Thanks for reading all of these questions. -- Martin

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1996 F-150 5.0 w/Superchip, K&N air filter, Motorsport 9mm plug wires, LineX bed liner

 

moose man,

an OBD-II sensor reader is basically a device to read the trouble codes off of the trucks computer when the Check Engine light comes on. OBD stands for OnBoard Diagnostics and the II is that this is a second generation of this computer.

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'97 F-150, 2WD, 8'bed, 4.6L,Auto, 3.55 LS, Duraliner, D. plate toolbox, K&N filter, 3" air box mod, silencer removed, Westin nerf bars,towing pkg,headlight flasher