When checking without driving a while first, my codes are P0101, P0155, & P0155 pending.
After driving for a while, I check the codes again, and the codes are P0101, P0155, but also P0101 pending and P0155 pending. Why would it show both codes twice, and pending if they show them first as not pending?
Especially because when it has not been driven the code P0101 is shown not pending, only shown as regular P0101. It only goes to P0101 AND P0101 pending after the truck has been driven for a while.

 

p0101= insufficient flow through MAF sensor. P0155= O2 sensor heater circuit malfunction bank 2 sensor 1.

A pending code just means the criteria for setting the code hasnt been reached yet but has some counts towards it. If a code exists for a period of time and the code doesnt reoccur it erases the code. Pending just means its reoccurring, therefore its not going away on its own. A pending code is nothing to worry about on its own, usually just a fluke.

 

the I/M readiness check shows my Catalyst is "not ready". It has show that the past few days, even after the truck has been driven a lot. Does this probably mean it has not been performing the I/M readiness check for the Catalytic converter at all? If so, I think that might prevent my truck from passing inspection

 

it cant do the test because the o2 sensor isnt working. You cant pass with the check engine light on

 

DTC's need to be diagnosed and repaired one at a time, always starting with the first one. Subsequent DTC's can be falsely set by the first DTC. After each repair the DTC's need to be cleared and a General Motors Driving Cycle completed to verify the repair. The drive cycle will force all monitors to run and complete their test. If the check engine light comes on before, during or after the drive cycle, repeat the process starting with the first DTC.

The PCM monitors certain circuits continuously, (throttle position, crankshaft position, MAP, MAF, misfires, etc). Others are monitored only under certain driving situations, (oxygen sensors, oxygen sensor heaters, EVAP, intrussive air, fuel trim, EGR, etc). Those monitors are the systems that are reset when the DTC's are cleared. They require a drive cycle to be completed to run and complete each monitor.

Clearing the DTC's resets all of the monitors: When you go in for the emission test, if the check engine light is on, the vehicle will fail. The next thing they check is the monitors. If any of them are incomplete, the vehicle will fail.