Service engine soon light is on

Tiny
MARIOB539
  • 2004 FORD EXPLORER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 100 MILES

I have the XLT model. The "service engine soon" light keeps coming on. I understand this light may come on when the vehicle reaches a certain mileage. My vehicle has reached 125,000 and this light has been coming on/off around that mileage area. I disconnect the battery for several minutes and it is off, after a few days it returns.
i replaced everything in regards to electrical. Starter, plugs, plug wires, EGR valve, belt, belt tension-er belt pulley and alternator.

Maybe it is not engine problem? Maybe oxygen sensor, that was never changed.

what else could this be? Thank you in advance.

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Sunday, April 17th, 2011 AT 11:09 PM

21 Replies

Tiny
RASMATAZ
  • MEMBER

Have the computer scanned for code/s-you have a problem within the engine management system that caused the CEL to turn on. This is your starting point of diagnosis, finding out what is going on.

Follow this guide to help find the problem code:

http://www.2carpros.com/articles/service-engine-soon-or-check-engine-light-on-or-flashing

Please let us know happens so it will help others.

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Sunday, April 17th, 2011 AT 11:14 PM
Tiny
CARADIODOC
  • EXPERT
  • 28,980 POSTS

First of all, you are confusing the check engine light with the older "maintenance required" light that was used in the 1980's with truck emissions systems. The check engine light means the engine computer detected a problem and set a diagnostic fault code in memory. You erased those codes and lost that valuable information when you disconnected the battery.

Most of the parts you guessed at and replaced have nothing to do with the check engine light. Namely, the starter and generator have nothing to do with the engine sensors and emissions system. As Rasmatz indicated, having the fault codes read is the place to start. Many auto parts stores will do that for you for free. They will get you into the right circuit or system with the problem, not necessarily the defective part.

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Sunday, April 17th, 2011 AT 11:54 PM
Tiny
CARADIODOC
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Change the wiper motor and brake light switch too as long as you are going to guess. There are a dozen computers on your truck all with multiple sensors and switches. Two computers are involved in blowing the horn. A computer is involved in running the power windows and locks.

There are over a mile of wires in your truck. Any one of them can rub through and short out. Computers commonly fail. Sensors can feed incorrect information to those computers. This is why mechanics must continually go for update training. Every time you replace some random part, you are introducing a new variable that can confuse multiple computers.

You are not going to solve this by replacing parts. Start by having the fault codes read. That will save you the expense of all the unnecessary parts.

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Monday, April 18th, 2011 AT 12:09 AM
Tiny
MARIOB539
  • MEMBER

I was just guessing and replacing parts randomly. I did this because it was time to replace before they went and all replaced with Ford parts. I am going to the store today and get diagnosis. Thanks to all.

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Monday, April 18th, 2011 AT 12:18 PM
Tiny
CARADIODOC
  • EXPERT
  • 28,980 POSTS

Boy, I sure sounded sarcastic. Sorry about that. Do not do the "random" thing. That is the most expensive, least effective way to diagnose a problem. First of all, there are some parts that have a history of almost never needing to be replaced. Doing so is money wasted, but more importantly, everything you do or replace adds another variable to the problem. Some sensors require precise air gaps to work properly. If one is not set right, you could now have two problems. Also, many resistance sensors such as throttle position sensors and any temperature sensors will never have the same resistance between any two of them. The engine computer learns their characteristics by comparing their readings to other sensor readings. For one example, the computer knows that the coolant temperature sensor and the intake air temperature sensor have to be reading the same temperature after the engine has been off for at least six hours. When it sees a different resistance from one of them than it expects, it has to figure out which one changed and put that new set of values in memory. That will not occur if it thinks there is a problem with the other sensor so you could introduce a running problem just from removing a good sensor and replacing it with another good one.

The best approach, since the check engine light was on, means at least one diagnostic fault code has been stored in the engine computer and having them read will get you into the circuit or system with the problem. There might not even be a defective part. You could have an EGR, (emissions) tube that is plugged with carbon, a leak in the fuel supply system that is letting vapors evaporate, a sensor problem, or a sensor could be detecting a problem. Someone here will be able to give you direction once we know which fault codes were stored in the computer. Many auto parts stores will read them for you for free.

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Monday, April 18th, 2011 AT 9:54 PM
Tiny
MARIOB539
  • MEMBER

LOL! Thanks for information going to a auto store this afternoon. I will say this, my Ford has 125,000 on it and it is seven years old, but looks show room condition. The truck took me home every time! And I went all over the place even in the mountains and it helped me drag my friends car out upstate New York. If it is something serious and costly it may be time to send it to its final resting place. We will see. And thank you for the input. Always appreciated!
Mario

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Tuesday, April 19th, 2011 AT 11:16 AM
Tiny
CARADIODOC
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Seven years old is not time to retire it. I have three newer vehicles, (I mean newer than 1988), but I only trust my 1988 rusty trusty Grand Caravan to get me home after numerous cross-country trips. I regularly drag a tandem axle enclosed trailer that is bigger than the van, and it is only had one transmission fluid and filter change in its life of 225,000 miles. It did not get me home for the first time in its life a few months ago due to a bad ignition coil, but I had eleven months of warning with intermittent stalling.

To add to the abuse, I have not pulled the oil drain plug in over eight years! I add a quart about every 1,500 miles and change the filter, oh, about once every three years, if I am feeling generous! I would not dare treat my other cars like that.

The point that I am not making is I would rather see someone fix an older car vs. Buying something new. The engineers have figured out too many ways to cost us money with their current products and I refuse to have any part of it.

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Tuesday, April 19th, 2011 AT 11:17 PM
Tiny
RPARKINS
  • 2000 FORD EXPLORER

Six cylinder four wheel drive automatic 130,000 miles.

Check engine light on and idles rough when cold.

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
DAVE H
  • EXPERT
  • 13,496 POSTS

Hello, thanks for the donation much appreciated.

Take the vehicle to a good auto parts store (Autozone etc.) have them read the cars computer for fault codes (most do this free) re-post with the codes for a better diagnosis and repair information. the fault could be due to any number of sensor's etc. on the vehicle. hope this helps. let me know.


http://www.2carpros.com/forum/automotive_pictures/266999_AAA2_127.png

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
BLACKBEAR55
  • 1998 FORD EXPLORER

Six cylinder four wheel drive automatic 133,000 miles.

My check engine light is on what can it be?

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
MHPAUTOS
  • EXPERT
  • 31,765 POSTS

Hi there,

The check engine light is a visual indication that the ECU has logged a fault code. You will have to get a scan done to read this code as it will be an indication as to where the problem lies.

Mark (mhpautos)

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
JBLB2009
  • 1998 FORD EXPLORER

Six cylinder four wheel drive automatic 255,600 miles.

I have the XLT model. I have the check engine light on always and my gear changing slips and clunks sometimes. The car feels like its losing power during acceleration sometimes.

I have had a new transmission put in and have had the car at the transmission's and auto electrician three times, it came back fixed but last for two day's and the check engine light comes on again with the same gear slipping problems.

Any idea's?

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,423 POSTS

Have they told you what the code was when the computer was scanned?

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
JBLB2009
  • MEMBER

No they have not, I have been told now that its not the transmission but an electrical problem. There was a problem with the speed control sensor which has been replaced but the problem still kept coming back after a few hours of driving.

It is believed there could be a problem with the transmission computer. I was told that when they done a live scan it was showing the rev's jump from 6000 rpm to 3000, to 4000. It was jumping all over the place.

Any idea's on this?

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,423 POSTS

I hate to say it but chances are the controller is bad.

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
JBLB2009
  • MEMBER

What exactly is the controller? I have no idea in this type of situation. Are they expensive to replace if this is the problem?

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
  • 68,423 POSTS

It is basically a computer for the transmission. It is located (I believe) on the transmission.

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
RICKYSH11
  • 1999 FORD EXPLORER

Six cylinder two wheel drive automatic 159,960 miles.

I have been experiencing a shaky engine, loss of coolant without any leaks, and the smell of burning oil. The check engine light flashes on and off and it read a misfire on the cylinder two when the check engine was scanned. I have had the plugs and wires replaced but it seemed to make little difference in the performance. Now the truck will not move when in drive nor reverse, but when in drive 2 it will move.

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
KHLOW2008
  • EXPERT
  • 42,061 POSTS

Hi rickysh11,

Thank you for the donation.

Symptoms of the engine misfiring and coolant losses indicates a possible head gasket problem. Get a pressure and compression test done to check if they are within specs.

As to the transmission, it seems to have failed. One of the clutches is bad and you would need to perform a line pressure to verify.

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Thursday, December 22nd, 2016 AT 4:30 PM (Merged)
Tiny
TYRYN99
  • 1996 FORD EXPLORER

Six cylinder front wheel drive automatic 168,000 miles.

My check engine light came on so I took it to the shop for a diagnostic. The findings were that I needed to replace both O2 sensors on the passenger side. I had that done. The engine light went off for about an hour than came back on. I had another diagnostic and it said O2 sensor unplugged. The same mechanic re-checked them and says they are fine. Do you have any suggestions as to what the problem could be?
Other than the check engine light being on my truck runs well.

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Thursday, December 22nd, 2016 AT 4:31 PM (Merged)

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