1996 Ford Ranger computer won't cycle all the way through

M WORST

MEMBER
1996 FORD RANGER
4 CYL
2WD
MANUAL
155,000 MILES

Had to replace O2 sensor and reset the computer, I then drove it for two days, on and off the freeway without getting a check engine light. So I went to get a smog check and it failed do to the computer not completing it's diagnostic testing. How do you have to drive it so the computer will perform their diagnostic testing so all the monitors get checked. I ran it through my INNOVA 3100 OBD2 code reader when I got home and it shows catalyst monitor, oxygen sensor monitor, oxygen sensor heater monitor, haven't ran yet. What can I do to get it to reset so it will smog. Michael L. Worstman

2 Replies

98RANGERXLT

MECHANIC
301 POSTS

Start it up cold drive it till it reaches operating temp shut it off start it up cold again that is a driving cycle if that dont work then unhook the batt for a few minutes then hook back up.

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Saturday, April 26th, 2008 AT 9:39 PM

BMRFIXIT

MECHANIC
19,053 POSTS

Drive cycle will be complete and system ready only when the PCM run all test
it may take up to 300 miles or more a week or two of regular driving
if it still saying that the o2 sensor not ready then the PCM have not determined if that sensors is OK or not
and they still under test
resetting the computer or disconnecting the battery will only put you back at the starting point
make sure the engine is reaching operating temperature and thermostat + coolant sensor OK
start cold engine let it idle for about few min
then take it for a long ride 80 100 mile
try to hold steady speed for a few miles and over 45MPH

then at the end of the trip test if system ready and DO NOT turn it off