Duane

My check engine light comes on after startup. It doesn't blink. It just comes on and stays on. After checking the manual, gas cap is fine, fresh tank of gas put in in case of water in fuel. But light still stays on. The manual seems to be pretty vage about what it could be. Do I just need a diagnostics done? Because the truck appears to be running fine without any trouble. Anybody have experience with this issue??
Thanks in advance.

techrep

iTrader: (1)

Drive by your local auto zone / advanced auto/ O rileys/ pep boys.....they will read your codes for free. Or you can buy a code reader very cheap now days. good luck

Duane

Code reader?? So this is a device that will connect to my engine and give me a reading of what the problem is?

bobkyle2

Yeah.. It will connect to the obd port under the dash....

Duane

So what's a good brand name device that would be a good one to buy if I chose to buy one?

JimFX4

Your CEL comes on and stays on after start up b/c the problem still exists. The CEL will only claer if the problem is gone within a few drive cycles. Your engine ignores computer readings until the system is in closed loop (CAT is @ 600+ degrees). Given that it is not flashing, you no that it is not a mis-fire. A mis-fire causes the CEL to blink.

Duane

Ok... so I'm not a mechanic. I really appreciate the help, but can you explain what you mean by "the the engine ignores computer readings until the system is closed loop (CAT is @ 600+ degrees)"???
Thanks

PR.F150

Like techrep said, drive by Advance/AutoZone/O'Reilly's. They check it for free. Not worth buying a code scanner at this moment in time if you didn't even know how to pull a CEL code.

Get your code read, then google whatever your code is. PXXX. It could be a wide variety of things.

As for closed loop, that's just another way of saying the ECU reads the a/f mixture mainly based off the O2 sensors, or warmed up under normal conditions.

Open loop would be when the car is still warming up or under really heavy load.

Duane

Ok... I'll get with Auto Zone or Advanced and see what codes they pull up. I think I just found all the OBD ll trouble codes online. But I would suppose they would actually have a list of the codes avaialable right there at Auto Zone too if asked. Either way, I know I have to learn what code/codes come up in the scan before I can move forward with a fix.
Thanks to all for the great info!!

Mod (Ret.)

Once the auto store gives you the code(s), enter the code in the google search window. You will get several links; open each one until you find one that provides the code definition, and what to repair/replace to correct the fault. Be aware that most codes can be caused by several sensors, so it may require you to either replace one part at a time until the code clears (expensive way to troubleshoot), or pay a shop to do this. You will either need a diagnostic scanner (or tuner) to clear the code, or you have to disconnect the battery to force the code to clear. Removing the battery causes the PCM (powertrain control modue) to have to "re-learn", so your idle may be rough until you drive a few miles at several cycles.

Most repair shops have "test" sensors that they use to identify which part is causing the fault, then they replace the part with a new one once the faulty part/sensor has been identified. You pay labor costs plus parts, but it may be cheaper than you replacing one part at a time until the code will clear.