Subaru p0851 adjusted switch light stayed off for nine miles than come back on also readyness monitors only 3 get ready evap and egr wont

Some advanced scan tools have the ability to shorten the time to reset monitors. You won't find this scanner at Auto Zone. My snap-on cost Ten grand.

Have a look on the following link:
https://subaru.oemdtc.com/58/diagnostic-procedures-for-p0851p0852-2005-2008-subaru

broken evap line/port on fuel pump. Or leaking fuel pump o-ring
check the EVAP canister it is right next to fuel filter could be pcm needs update to fix false codes. Here is a old hillbilly trick that may help put saliva on the seal of gas cap when you fill up every time that may work for you.

This is my drive cycle a generic drive cycle i have used many times over the years and it has never failed me most drive cycles are too specific and impossible to adhere to for most drivers follow these steps exactly 1. make sure all codes are cleared and no check engine light is on 2 make sure the fuel level is between 1/4 and 3/4 full (this is part of the enable criteria for the evap monitor to run ) 3 let vehicle set overnight 4 start engine and let idle until the temp gauge is in the middle (this cold start enables the evap monitor and runs the O2 sensor heater test )5 drive vehicle around town avoid the highway stay at below 50 mph and when stoping at lights remove your foot from the gas and coast from around 50 to about 10mph or less if possible this will run the EGR monitor after about 3 to five miles of this proceed to the highway or freeway and travel over 50 but under 70 mph for about 3 to 5 miles this will run the catalyst test provided the O2 monitors passed if they didnt you will have a check engine light on before this point also i do a coast down on exit ramps (no braking) they make great places to get that EGR to run ONCE YOU START THIS PROCEDURE DO NOT KILL THE ENGINE OR SOME OF THE TEST WILL FAIL TO RUN

All you have been doing is clearing the check light on dash &
clearing the obd codes,not diagnosing anything related to
the codes or trying to solve the problem

The Evap Monitor will run when ever it should, based on how
that is programmed into the vehicles computer,no need to drive
80 miles or any miles

You should have a codes for the Evap Problem, if you stop clearing them & that also has nothing to do with an EGR Issue

It is not how far you drive it is how you drive. Google this to read more about it Google "OBD 2 Drive Cycle"

In order to set the monitor it the drive cycle 2 trip criteria that means you need to have a cold start up and reach operating temperature then another cold start up with a operating temperature reached and the drive for each one is part throttle hold for 2 miles and a decelration for the catalytic to get ready.when the cat is ready the evap runs.If you are loosing monitor at key off and everything reset you can see the referee let them smog it. The EGR and EVAP are almost impossilbe to get ready

U have to operate the engine at all kinds of diff speeds and drive modes, it is called a OBDII drive cycle, here is how u do one.
1. As soon as the engine starts, idle the engine in drive for two and a half minutes with the A/C and rear defrost on. OBDII checks oxygen sensor heater circuits, air pump and EVAP purge.

2. Turn the A/C and rear defrost off, and accelerate to 55 mph at half throttle. OBDII checks for ignition misfire, fuel trim and canister purge.

3. Hold at a steady state speed of 55 mph for three minutes.

OBDII monitors EGR, air pump, O2 sensors and canister purge.

4. Decelerate (coast down) to 20 mph without braking or depressing the clutch. OBDII checks EGR and purge functions.

5. Accelerate back to 55 to 60 mph at half throttle. OBDII checks misfire, fuel trim and purge again.

6. Hold at a steady speed of 55 to 60 mph for five minutes.

OBDII monitors catalytic converter efficiency, misfire, EGR, fuel trim, oxygen sensors and purge functions.

7. Decelerate (coast down) to a stop without braking. OBDII makes a final check of EGR and canister purge

can't locate idle control sensor on 1998 Chrysler Town& Country van

Rich:

The trick to setting all the monitors is:
Make sure you have more than 1/4 tank of fuel but no more than 3/4.
Clear codes then Do Not cycle key off. Start vehicle and drive,make sure you do at least 2 minutes of steady spead between 40-50 mph and at least 2 minutes at 50-65 mph, usually about a 20 to 25 mile drive will set them..
If you turn the ignition off before the monitors complete then EVAP will have to see a 6 hour cold soak before it will attempt to run again.