Check engine light goes off/on randomly

Tiny
RYLOS04RANGER
  • MEMBER
  • 2004 FORD RANGER
  • 90,000 MILES
Had a friend put a code reader on it and it says #4 cylinder is not fireing. Works fine. Seems to run good when light comes on. Sometimes when I start the vehical it seems like it is running on four cilinders. I'll turn the key off and restart the moter and everything is fine. Checked wiring harness and found no problems. Just runs wierd at different times. Idleing, shifting, gas consumption, no continuos pattern. Please help, thank you
Saturday, September 17th, 2011 AT 10:18 AM

17 Replies

Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
This is common where there is a trouble code this video should help us.

https://youtu.be/InIlnsjOVFA

Please run down this guide and report back.
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Saturday, September 17th, 2011 AT 2:11 PM
Tiny
RYLOS04RANGER
  • MEMBER
  • 4 POSTS
3.0 v6 2004 automatic dont have multimeter but will get one if need be. Only visually checked all wiring harness plugs for burnt or loose wires. Changed plugs and plug wires. If it is the coil pack would it affect shifting also? Thanx for your response
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Saturday, September 17th, 2011 AT 8:37 PM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Yes it could and it would run very badly too. Do you have a digital multi meter to do a couple of tests on the coil pack?
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Tuesday, September 27th, 2011 AT 4:20 AM
Tiny
RYLOS04RANGER
  • MEMBER
  • 4 POSTS
Yes, I have multi-meter. Thank you for your time and response. Ready for instructions.
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Tuesday, September 27th, 2011 AT 6:24 PM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
First unplug the coil pack harness. I then need you to check for voltage we want at least 10 volts ok. Use the chart below to identify your connector then put the meter between the ign start/run and ground what is voltage?
Image (Click to make bigger)
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Friday, September 30th, 2011 AT 3:51 PM
Tiny
RYLOS04RANGER
  • MEMBER
  • 4 POSTS
Meter reads above 14. Same for the rest of the wires on that connection.
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Saturday, October 1st, 2011 AT 9:36 AM
Tiny
RACEFAN966
  • MECHANIC
  • 5,029 POSTS
Ok let me do some more digging and see what to do next.
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Tuesday, December 13th, 2011 AT 8:27 PM
Tiny
ANDREW F. MADISON
  • MEMBER
  • 1 POST
  • 2004 FORD RANGER
  • 4 CYL
  • 4WD
  • AUTOMATIC
  • 76,505 MILES
I have 2004 Ford Ranger Edge. How do I reset engine light?
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Friday, November 27th, 2020 AT 9:52 AM (Merged)
Tiny
SATURNTECH9
  • MECHANIC
  • 30,869 POSTS
On that model you would use a scan tool to reset it if you don't live in california you could take it to a auto parts store like auto zone and they will do it for free. But if the light is on then you most likely have a problem and the light will come back on sooner or later. Find out what code's you have and let me know the exact code number's.
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Friday, November 27th, 2020 AT 9:52 AM (Merged)
Tiny
SWHITECAT
  • MEMBER
  • 2 POSTS
  • 2004 FORD RANGER
  • 93,000 MILES
I changed the spark plugs due to hard starting. Upon completion, the rough idling began, and the engine light came on. The plug gap on the old plugs was substantially off.

The change of plugs seems to correct the hard starting, but now I have the problem of the rough and irregular idling, along with the engine light being on.
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Friday, November 27th, 2020 AT 9:52 AM (Merged)
Tiny
MADMIKE1735
  • MECHANIC
  • 951 POSTS
You will need to get it scanned and let us know the codes. If its misfiring, it should set a code indicating which cylinders are misfiring, and should be easy to fix. Also, what size engine in this?
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Friday, November 27th, 2020 AT 9:52 AM (Merged)
Tiny
SWHITECAT
  • MEMBER
  • 2 POSTS
The Ford ranger has a 3.0 Liter engine
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Friday, November 27th, 2020 AT 9:52 AM (Merged)
Tiny
MADMIKE1735
  • MECHANIC
  • 951 POSTS
Ok. You will still need to get it scanned though, and let us know what the codes are.
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Friday, November 27th, 2020 AT 9:52 AM (Merged)
Tiny
BUMEDOUT
  • MEMBER
  • 2 POSTS
  • 2004 FORD RANGER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 84,000 MILES
My check engine light came on the other day. I took it to the service center and they put the meter on it and said the code showed a bank 2 oxygen sensor was bad. They said it had two and they would not know until they ran a full diagnostic on it. They said the full repair should cost around $215.00.

My question is since the truck is running good with no miss or loss of power, what would it hurt to continue driving with the light on?

Second question. Should I go to Auto Zone and purchase two oxygen sensors and put them on?

I called Auto Zone and they have the part for $43.99 each.
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Friday, November 27th, 2020 AT 9:53 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Chances are your fuel economy will suffer. As far as the parts, the computer code that is set should identify which one is bad. I doubt both went bad at the same time. Thus, have AZ scan it for you. Most of them scan for free, and yes replace it yourself. It is just a matter or unpluging the sensor, screwing it from the exhaust and replacing the new one.

Let me know if you have other questions.
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Friday, November 27th, 2020 AT 9:53 AM (Merged)
Tiny
BUMEDOUT
  • MEMBER
  • 2 POSTS
I took my Ford Ranger into the shop to see why the check engine light came on. They ran the diagnostics and said the code showed the Oxygen Sensor behind the the catalitic converter. I bought one and put it on. The light stayed off for about 3 days and came back on. At that point I said I am going to get rid of this lemon before something else goes wrong.

The gas mileage is bad. Does anyone have any suggestions of what I should do short of getting rid of this thing.
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Friday, November 27th, 2020 AT 9:53 AM (Merged)
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
I would take the car to a nationally recognized parts store to have the computer scanned again. Most will do it for free. That way you will know if you got a bad part.
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Friday, November 27th, 2020 AT 9:53 AM (Merged)

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