check eng. light on

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Jan 14, 2001 | 08:23 AM

mkf

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check eng. light on

I have a 96xlt 351 the check eng. light is on I know it sounds nuts but I thought I had a connection problem at the battery, I removed the cables from it and cleaned both the light went out and then returned 3 day later. I now see from the board that it my be a o2 sensor problem, I went to the auto store and they asked if I had two sensors or one, before and after the cat. The question is? why does the light go out for a couple of days if I dissconnect the battery? thanks for any help

Jan 14, 2001 | 03:04 PM

nitro94

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From: Wichita USA

check eng. light on

The light goes out because you have dumped the ECM memory by disconnecting the battery. Some selftests take several trips before the ECM considers it a fault. Have the codes read so you have an idea of what is wrong.

2000 XLT Flare Supercab Sport 5.4-Auto-355LS-Tow pkg-Bedrug-Xtang Tonneau

Jan 14, 2001 | 06:38 PM

AlM

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check eng. light on

yes, have it scanned or do it yourself if you feel comfortable doing it..lost my self test bookmark, so maybe someone else can post the url for you here.
also, read your Owner's Manual..some simple things are stated there such as:
"loose gas cap..yep!
intalling a CB radio, alarm, cell phone and wiring too close to the PCM or components"

does it light up when you have the ign key "ON"?? if not, manual says it is prob an emissions prob

does it turn off and on @ one sec intervals while driving? if so, could be "engine is misfiring" and "damage could occur to the engine or cat. converter"

if cel turns off and on "on rare occasions while you are driving..."
could be cause by "engine running out of fuel"
or ..plugged filter..etc...
manual says that ..."4 warm up cycles" are needed before the CEL will turn off"......each cycle consists of starting engine at ambient conditions..say a few hours in cold weather between start ups.
good luck!

Feb 14, 2002 | 12:40 AM

broncoman2000

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From: tucson usa

check eng. light on

Yeah I have a 96 Bronco 351 also and you actually have 3 O2 sensors 2 before the cat. and 1 after the cat. It sounds like you are having the same problem as me i replaced the corroding + battery cabe which was $130.00 specially ordered from the dealership and it still didnt fix the problem. as for the check engine light showing up 3 days after resetting it, it seems to me that it likes to pop up after 3 start-ups, and the check engine light wont show up after 1 start up and 40 min. of driving. I retrieved the diagnostic codes and they say its an O2 sensor heater circuit malfunction for all 3 sensors and it says the system is too lean. If you find anymore info on this problem please e-mail me at rob9018(No Email Addresses In Posts!)
Hope this gives you a clue of what is going on.
,Robert

Feb 14, 2002 | 04:43 PM

Rodeojoe

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check eng. light on

I had the same problem with my check engine light and the o2 sesors. The mechanic I talked to told me if you disconnect the battery it will temporarily reset the computer. The codes will still be in the memory until it is cleared with the obdII computer. I had replaced the o2 sesors(with the battery diconnected) and after running it a couple of times on short trips the check engine light came back on.

. The obdII then said it was my egr valve. Replaced that. The Bronco was still running rough (no check engine light) so I took it to anther mechanic,( got tired of the truck nickle and diming me to death), and the DPFE sensor was replaced.

Rodeo Joe

Feb 14, 2002 | 07:50 PM

kyle11

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Joined: Feb 2000

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From: Dallas

check eng. light on

>I have a 96xlt 351 the check eng. light is on I know it
>sounds nuts but I thought I had a connection problem at the
>battery, I removed the cables from it and cleaned both the
>light went out and then returned 3 day later. I now see from
>the board that it my be a o2 sensor problem, I went to the
>auto store and they asked if I had two sensors or one,
>before and after the cat. The question is? why does the
>light go out for a couple of days if I dissconnect the
>battery? thanks for any help

Well, I've never heard of 3 O2 sensors...interesting. My 5.0 only has one, but I can offer a diagnostic suggestion. Try unplugging and driving around with 1, 2, and then all 3 sensors unplugged for a couple of laps around the block. You may not see any difference in the light, until you plug them all in again. If not, it would seem to be bad EGR valve, EGR sensor, or vacuum hose to the EGR valve. The valve is $86, by the way, and is usually not the problem.