Having problems with 4.6L engine running rough. Last year dealer replaced the MAF, then the van ran rough 2 weeks later and they said it was the "left front bank sensor". Was running ok and I finally replaced the sensor, now it runs rough and the check engine light comes on and flashes sometimes. Took it to Advance and when they hook up the code scanner, it does not register? They hooked the scanner to their delivery truck (not Ford) and it worked. Is there a fuse for the ECM? Should I just replace the "right bank sensor"? These are after the catalitic's so I think they are "downstream"(?) and the dealer replaced one "upstream"(?) are there only 3?

Sorry for wandering from ECM to sensors.

 

I'm pretty sure the important o2 sesors are the 2 in front of the cats. they are the one the computer makes adjustment from the other 2 and you should have 4 just report. Try disconecting you negitive terminal on your battery for 5 minutes. Sometimes they need to reboot..

 

Yes, there is a fuse for the OBDII port. Starting in 99, it was on the same circuit as the cigar lighter for a couple of years.

Unfortunately, you didn't identify your vehicle adequately so I can't look it up. Should be in your owner's manual.

Don't screw with the O2 sensors, they won't cause your symptoms. You probably have the all-too-common vacuum leak from the PCV hose elbow or a common misfire.

Steve