Make Ford
Year 2003
Model Mustang
Engine 4.6L 4V
Transmission 6 sp manual
Symptoms EGR and CATALYST monitors not ready
Codes NONE
Unusual Operating Conditions NONE
What you have tried Following the published drive cycles for nearly 300 miles without PCM reset

Long story short, I have a 2003 Mustang that will not set the readiness monitors for EGR and CATALYST after approximately 300 miles of driving. I've been able to get the remainder to set.

I'm well versed in the "Ford drive cycle" and have performed my interpretation of these drive cycles a number of times over the 300 miles. Other than the obvious P1000, there are NO codes set - no indication of what might be holding the monitors out. The car has some performance modifications, but none that should impact the OBD systems; although the lack of codes is making this more difficult to determine.

Two questions:
  • Can anyone translate the drive cycle requirements for EGR and CATALYST in to things I can observe with my Snap On MT2500 scanner to determine what is holding out the monitors? That is, I know that EGR requires 3 accelerations from 0 - 45 mph at 1/2 to 3/4 throttle, but what PIDs, sensors, and values is the PCM actually looking at to see if I've met this requirement? Is there a more detailed/technical description available? Same for the CATALYST monitor. I've searched the 'net and looked through the Ford service manual for this vehicle and have not found a more technical description.
  • I was wondering how EXACT the drive cycles have to be in order to get the readiness monitors to set. For example, to set the EGR monitor, three 0 - 45 mph accelerations are required at 1/2 to 3/4 throttle. On a manual trans car, shifting from 1st to 2nd during this acceleration is going to release the throttle to less than 1/2. Will this interrupt the drive cycle? Likewise, the CATALYST monitor requires stop-and-go driving with 5 constant cruise speeds between 25 and 45 mph over a 10 minute period. If I come to a complete stop at all during that period (which is the nature of stop-and-go driving, after all), is the drive cycle interrupted?


Thanks. Any thoughts would be appreciated to help in solving this problem.