The check engine light is on


Asked by Jun 12, 2013 at 12:36 PM about the Ford Ranger

Question type: Maintenance & Repair

Changed plugs and fuel filter, disconnected the battery in the process. check engine has
come after running about an hour around the neighborhood

6 Answers

Tracy Hooks

The Check Engine light is an indicator from the Powertrain Control Module (PCM) that something is out of specs within the computer controlled system. Hook up a scan tool and retrieve the DTCs (Diagnostic Trouble Codes) and go from there. Be aware that a trouble code doesn't necessarily mean that a component is bad except in a few cases. It means that there's a reading or signal that is out of range.

18 out of 18 people think this is helpful.
Sean Hensley

Agree with Tracy. Autozone, Advance, and Oreillys (or other chain parts house) all should offer free diagnostic testing, as well as the part(s) and rental (or for purchase, if you choose) tools to fix it, and might even help or change it for you. Might try plain gas and checking gas cap, as well. Friend had the same problem and did 100% plain fuel and tightened the cap, which corrected it for him (won't always work, wouldn't hurt to try though).

8 out of 8 people think this is helpful.

My 2002 Ranger was doing the same thing. I attached a code reader to the computer under the steering column and it was able to diagnose the problem as well as its general location. Turned out one particular cylinder(#4) was running LEAN which its cause could be anything from a bad spark plug, to a vacuum or air intake leak, to a timing issue. (Lean=too much air not enough fuel...Rich= the opposite). This at least gave me a starting point, i knew to look for an issue on the cylinder#4 side of the engine. Always look at the simple most likely things first. After a basic, yet thorough, visual and audial inspection of the engine compartment (both with and without the engine running), i was able to locate a pinhole leak in a vacuum line. Simple fix, cost about ten dollars for a quality piece of new vacuum hose, took me about ten minutes to replace and has run great since. Here's my advice, 1) Go to any major auto parts store, and have them pull the vehicle's computer codes. This usually takes about five minutes and is typically free of charge. 2) The code reader will give a basic diagnosis and general area of the problem. It will read something like, for example(when I pulled codes on my Ranger): Cylinder #4 running LEAN. or "This Particular" Sensor is not working or Cylinder #X ignition failure etc. 3) After diagnosis is complete, you should have a better idea of where to begin. During this step, it is very important not to over think your evaluation, its always best to begin with the simplest, most likely causes to that particular problem...If you have no spark, start by checking that the battery is charged and properly installed (even a battery connection that feels tight by hand may NOT be tight enough to make contact "personal experience, embarrassing"), then go to the next step; inspect all wiring relative to the battery, ignition coil, starter, and distributor looking for any loose or corroded connection points and checking the overall condition of wires themselves. Any sign of worn insulation on any wiring may point to a potential trouble area and should be replaced. All this should be checked before you can even consider the plugs themselves being the problem. 4) Once the problem is fixed, you will HAVE to hook up a code reader again to reset the codes/computer. Your check engine light will turn off. If it comes back on, usually while driving, after repairs have been made and codes reset, then you have another problem other than whats just been fixed. Pull the codes and start the process again til all issues are fixed. Note: Code reader is required to reset computer in order to turn off check engine light. Also, check engine light will continue to re-appear until ALL problems are fixed. Just check the codes each time for a diagnosis and go from there.

23 out of 23 people think this is helpful.

VACUUM LEAK TEST SHOWS LEAN DO NOT REPLACE YOUR 02 SENSORS ON THE 4.0 you will find 3 elbos 2 are on the passenger side one on drivers side . Ford sells a kit 2 elbos and the tube but also can go to orieilys auto. first elbo to check runs to you maf air intake if this one is not it under the plastic shield on top of your throttle body 3 bolts holding this on but so much more room when you do . 2nd hose down runs around to drivers valve cover check the hose under plastic cover first . can test with brake cleaner or by looking if you are not to old like me . happy motoring :)


Have a ford Ranger showing missing on both one and four cylinder on the exhaust side


I had my Mazda B2300 (same as ranger) engine lights on this morning. This afternoon when I came home from work. I decided to poped that hood open pushed all those vacuum hoses to make sure they are tightly connected... Pushed those spark plugs wires to be sure that they are also tight. I cleaned the battery terminals too. After all was said and done. I started the truck and to my surprise... Baboom the engine lights came on...for a second or two then went away. Test drove the truck for about 70 miles so far soooo good no engines be continued...

1 out of 1 people think this is helpful.

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