Service Engine Soon...

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  #1  
Old 09-30-03, 03:38 PM
GlassesRx
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Unhappy Service Engine Soon...

...gotta love those lights coming on. I have a '97 Lincoln Continental and ofcourse the light came on. I took it to a local mechanic, ran the diagnostics and it came up that the O2 sensor had low voltage. I'm going to replace the spark plugs now since it has just a tad over 86,000 miles on it. Going to replace it with Motorcraft Platinum plugs.
The question is, do you think I need to replace the O2 sensor or this should do the trick? I had the mechanic reset the codes. It's ok now...just wanted some professional advice. Thanks for your help everyone.
 
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  #2  
Old 09-30-03, 04:59 PM
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you will probably have to replace the o2 also but you can wait to see if it sets the code again or the check engine light comes back on again. just replacing the plugs is not really going to fix your check engine light if it had an o2 code in it, and it will probably come back on within a couple of weeks.
 
  #3  
Old 09-30-03, 05:43 PM
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O2 Sensors can play tricks sometimes and be slow responders. IF you have an O2 Sensor that is slow to respond then you will use more fuel than normal. And as Bejay said the light WILL come back on. The tune up is always a good idea and some will say that O2 sensors are a maintenance item as well. The least expensive thing to do it to wait till it sets a code to change them because on some vehicles they are quite expensive. For example we had a BMW (cant remember the year and model) in the shop where I used to work. THe manual said that ALL 4 O2 sensors were to be replaced as a maintenance item every 30K miles. The car didnt have this done and had 90k miles and the sensors were just beginning to fail. This saved the customer $2000.00 as the sensors are approximately $250.00 EACH. Quite rediculous i think.
Bottom line, if you get a code for an O2 sensor, change it. You will be ahead of the game.
Billy
 
  #4  
Old 10-01-03, 06:19 AM
Joe_F
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Tune ups never hurt, so go ahead with that.

I believe you will see the light come back unless you find the root cause of the problem....
 
  #5  
Old 10-01-03, 06:29 AM
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dude, i am not a ford tech, but low 02 voltage is not a 02 sensor failure, or a spark plug failure. It means it is running lean. Don't touch the 02 sensors or the spark plugs. look more for reasons why it is not getting enuff fuel. Start with a fuel filter maybe.....
 
  #6  
Old 10-01-03, 05:06 PM
mike from nj
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big guy---when a sensor dies(on some cars) they read dead lean, .02 volts constant, the sensors voltages aren't biased like on gm---unplug it and it reads low like that. so if this ford was a biased system, you'd be right, if it isn't, then it could be a bad sensor

also a leaking intake would cause a 'lean' code, as would a clogged fuel filter or a weak pump or even an exhaust leak before the sensor



joe---tune-ups hurt my wallet when they don't fix the problem
 
  #7  
Old 10-01-03, 06:28 PM
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O2 sensors can get lazy from in town(older folks driving)that can be made to respond properly after a good high speed highway run.You could also do a propane enrichment test to check the O2 sensor for response.A drip of water could have passed through an injector.Which O2 sensor was at fault?You have at least 3 maybe 4 on that car.Some times you can swap the sensor to see if the fault follows the sensor.O2 sensor readings can be off by exhaust systems being rusty or poor fitting.The sensor needs ground to operate and may not be available through the exhaust system.The ground wire at the O2 sensor will not make up for this lack of ground.A lso if the sensor were to be covered in dried mud it will not operate properly because it measures ambient o2 against exhaust o2.Fuels high in methanol can cause this code on vehicles not designed as bi fuel compatable due to the oxygen content in alcohol fuels.Just wait for the hydrogen fuel cells.Hey if I drove a Volvo my radiator would be a catalyst.
 
  #8  
Old 10-02-03, 05:24 AM
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mike: the code wasn't for an inactive, or dead o2 sensor, it was for low voltage. every vehicle i have seen with a feedback system since 1981, low voltage means lean.(assuming it is not a false indication). Ageeably if the circuit was grounded, the voltage would be low. So two things need to be checked: is the indication true, and if it is, why is it running lean..if it is not true, find out why, either a wire is shorted or the sensor is shorted.
 
  #9  
Old 10-02-03, 06:13 AM
Joe_F
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Mike:

Tuneups never hurt and 9 of the 10 cars I do it on were WAY overdue for it anyhow. You'd be surprised how many cars we did where the customer had never done any maintenance to the vehicle and in turn were like "That filter came out of my car??"

"Yes sir, sure did. No one's touched a thing here". I tune up my cars yearly and I can tell you that even in mixed traffic I'm hitting 24mpg with my Chevy Cavalier (and that's using it 45 miles a day in BQE traffic every day).

As I mentioned, it won't hurt. But as we are all saying, the problem is elsewhere.
 
  #10  
Old 10-02-03, 06:29 AM
duce110
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Joe F, I don't know if you remember but I was having the same problem with my Ford Explorer. I took it to a shop and they told me it was three out of four of my O2 senors. Luckly I had extended warrenty. Once changed the light came back on about 80 miles down the road. I took it to Ford and they told me some Fords are on recall because O2 sensors keep going off. The only problem I had was that I had a leaking intake manifold o-rings. They replaced it for free and I never had the problem since. Try checking into that.
 
  #11  
Old 10-02-03, 07:00 AM
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I CAST MY VOTE FOR TUNE UPS BEING WAY OVER RATED.......
IF THERE IS A PERCEIVED DIFFERENCE WITH AN ENGINE'S BEHAVIOR AFTER A TUNE UP SUCH AS POWER OR FUEL CONSUMPTION, IT'S ALL IN YOUR HEAD.....

NOW THAT I THINK ABOUT IT, I THINK MY TRUCK GOES FASTER AFTER I WAX IT.....
 
  #12  
Old 10-02-03, 07:15 AM
Joe_F
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Lol. Till you take out your spark plugs at 100k for your "extended tune up" and they are frozen in there. LOL. Some OEMs say to "take out the plugs and reinstall" at 50k. Why go through all that work to put dirty and bad parts back?

100k tuneups are a fallacy. The wires turn to dust and misfire in many cases well before that. I had the ORIGINAL ignition wires on my 30k mile (now) 89 Cavalier up until about a year ago.

When I say "tune up" I also mean "once over, servicing, fluid and filter changes". I find that if I stick my head under the hood often and regularly and keep up on things that I'm not the guy on the cellphone with his hood up in 100 degree traffic blocking up the lanes for everyone. LOL.

Cars still need regular maintenance .

BTW: I feel good when I drive a clean car. LOL
 
  #13  
Old 10-02-03, 06:26 PM
GlassesRx
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OK...thanks for all the tips guys. Like you all said, a Tune up never hurt anything. So off I went. I replaced the plugs..wow, first time since it rolled out of the dealer. The gap was no longer at .054, but at .070 or greater. Although I am not a mechanic, I was hoping maybe that can cause a low voltage reading for my 02 sensor? That's what I found for now, going to be nice to the car and change a few more things too. So far, the lights are clear. I'll keep you guys posted if it comes back on. Crossing my fingers!
 
  #14  
Old 10-03-03, 05:45 AM
kidsgolf
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First, congrats for making it so long without a tuneup! Second, remember that on a Ford the O2 sensor plays a HUGE part of the computerized adjustments. Never mind that Ford publishes "just fine tunes the mixture". On Ford for our Ohio e-check certain exhaust gases will be almost too high to measure; simply replacing the $25 O2 sensor (and $15 for the special slotted socket) brings those gases almost so low they can't be detected! Fine adjust my behind! On GM's they are just a fine adjustment, but not on a Ford. Oh and spending $25 every 50,000 miles to replace it (Ford, at least on my vehicle, only has one sensor on the exhaust manifold on the passenger side; GM uses a sensor in each exhaust manifold); Oh, replacing it every 50,000 miles will actually save well over $25 in gas by having the engine sensing and adjusting itself correctly. I know it sounds incredible, but I've been there and it's true! Gas mileage went up 10-15% after replacing it.
Oh, and also don't go too long between plug changeouts if you are using the Motorcraft or AC plugs. Reason - you'll end up snapping the half rusted through plug off and then have to extract the remaining threaded part. These guys are notorious for making plugs that rusted to the max on the thinnest part of the metal - just above the threads. Was there just last year, course I bought the Explorer used so I had no chance! Reminds me I'll soon have to do it to my F250.

But do think about replacing the O2 sensor(s) if not to expensive, on Fords they make a HUGE difference!
 
  #15  
Old 10-03-03, 06:51 AM
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original poster: make sure u come back and see us after u change the plugs and 02 sensors for further diag. on that low 02 voltage.....
 
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