Codes (??) Present

[imp]

It was remarked codes may be present with no CEL. I have no CEL, so today checked codes. 176, 177, and 212. HO2S "Full Lean", HO2S "Full Rich", and SPOUT grounded. Seems to me the car shouldn't run at all, much less very well.

It runs perfectly. Then, in my code reader instructions, I see Ford used OBD-II in '94 and '95, in "certain vehicles", code reader will not function in those vehicles. How would one determine if this Mustang has OBD-II? Wouldn't it have the newer style DTC socket? Mine has the old, with two connectors. The Emissions Certification code on the door jamb is 4-21A-ROO.

Any ideas greatly appreciated. imp

 

[Mustang5L5]

The V6's use OBD2

5.0's still used OBD1/EEC4


You may want to erase the codes, put a few miles on the car, and then rerun them. They could be old codes.

 

[jrichker]

How to clear codes.
Clearing the codes by pressing a button on the scan tool or disconnecting the test jumper used to start the code dump does not erase the “learned settings”. All it does is erase the stored codes in memory.

You must clear the codes anytime you replace any sensor. The following tells you how and is different from the method above
Clear the computer codes by disconnecting the battery negative terminal and turn the headlights on. Turn the headlights off and reconnect the all sensors including the MAF and anything else you may have disconnected. Then reconnect the battery negative cable.. This clears all spurious codes may have been generated while troubleshooting problems. It also clears the adaptive settings that the computer "learns" as it operates. Clearing the codes does not fix the code problems, it just gives you a clean slate to start recording what the computer sees happening.

Run the car for at least 30 minutes of driving and dump the codes again to assure that you have fixed the code problem or sensor problem. This is necessary for the computer to relearn the adaptive settings that the computer uses for proper operation. The engine may run rough at first, but should smooth out as it runs for the 15-20 minute learning period.