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Old 08-02-2007, 10:20 AM   #1
saagz87
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Need help with CEL light

So here's my situation. I went to auto zone to get my CEL code read. The code stated that both of my 02 heater circuits weren't working properly. So I got home, checked fuse 18 and it was blown. I replaced the fuse and it fixed the light, for a day! The fuse hasn't blown again but the same thing happens everytime. I pull the negative cable off my battery to reset the ECU and the light will stay off for as long of a trip as I want to take. However, as soon as i turn the car off and then back on. the light comes back on. I know the sensors are good because I'm getting good gas mileage so what am I missing? I think tonight I'm gonna get under my car and check the connections but the light should come on the first time I start the car if there is a bad connection.

Thanks guys


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Old 08-02-2007, 11:40 AM   #2
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the 2 o2 sensor your are talking about are for the cat monitering right, replace the sensors. those 2 don't do anything w/ air/fuel ratios. only the up stream o2 sensor(on the header) will help control a/f ratio. svt's are know for o2 sensor problems. you can always ohm out the heated circuit from the ecm to each o2 sensor connecter and see if there a open wire. if its good replace the sensors it replacing the sensor doesn't help you need to have you ecm updated or replace
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Old 08-02-2007, 01:09 PM   #3
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There is no way I would replace my ECU for just a light. I don't think the sensors have blown wires in them because the correct fuse was in the fuse box and it was blown. However, I will try and find the time tonight to do a continuity test of the circuit. Can I just test where the fuse goes in??? I know it won't tell me which sensor is bad but it would tell me if either of them are bad. The only reason I'm hisitant to do it is because I dont want to inject a current into my ECU and fry it with my DMM. Any suggestions???


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Old 08-02-2007, 03:35 PM   #4
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anyone???
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Old 08-03-2007, 10:22 AM   #5
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have you tried disconnecting the battery to reset your ecm?
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Old 08-03-2007, 11:10 AM   #6
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Quote:
Originally Posted by iammaxwell View Post
have you tried disconnecting the battery to reset your ecm?
he said he did in his first post.


As for why it's pulling a code.. just b/c you're getting good gas mileage does not mean the O2 sensor is good. I recommend replacing them. I bet that will clear up the issue. You'd get bad gas mileage if your second O2 indicated your cat wasn't working properly.


For example.. I'm getting a lot of O2 sensor slow response codes b/c the O2 is going bad.. but I'm not getting bad gas mileage...
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Old 08-03-2007, 11:39 AM   #7
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Ya, I figured I should just buy new sensors but it seems strange that both heater circuits went at the same time. Maybe when the fuse blew it ended up taking out both circuits? Fuse 18 is supposed to be a 10 A fuse right?

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Old 08-03-2007, 12:15 PM   #8
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Very strange man, my concern is that something is blowing the fuse. Check that the fuse is the correct amperage in the manual first. The code is from the open circuit (blown fuse) not the O2 sensor itself. You could try to replace the upstream O2 and see if it helps, but first I'd inspect the wiring, disconnect both O2 harnesses (the downstream is a bitch to get to) and spray them out with electrical contact cleaner. Plug em in when totally dry, inspect all wiring to see that nothing is obviously snapped/cut, disconnect battery and change fuses. Reconnect, start her up and take a spin. Come home, disconnect battery and check the fuse. Thats the most thorough pre-check list I can give you before you start throwing money at it.
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Old 08-03-2007, 12:33 PM   #9
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Quote:
Originally Posted by DougoeFre5h View Post
Very strange man, my concern is that something is blowing the fuse. Check that the fuse is the correct amperage in the manual first. The code is from the open circuit (blown fuse) not the O2 sensor itself. You could try to replace the upstream O2 and see if it helps, but first I'd inspect the wiring, disconnect both O2 harnesses (the downstream is a bitch to get to) and spray them out with electrical contact cleaner. Plug em in when totally dry, inspect all wiring to see that nothing is obviously snapped/cut, disconnect battery and change fuses. Reconnect, start her up and take a spin. Come home, disconnect battery and check the fuse. Thats the most thorough pre-check list I can give you before you start throwing money at it.
say what would be the best type of o2 to buy from autozone, and would that be causing my car not to go fast. i cant feel torque or anything???
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Old 08-03-2007, 01:04 PM   #10
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O2 problems can cause a lot of bad-running issues. Id highly recommend getting a motorcraft sensor. They are expensive, but talk to Mike in the Hilbish Ford section, he can get you one for much cheaper than the dealer.

Also look at rockauto.com - they have some wicked low pricing on some motorcraft stuff.
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