1998 Honda Civic: 3 sensors reading "Not Ready" when I go to get inspection. O2, Catalyst & Evap...any suggestions on how to solve issue?

O2 Emission Monitors & Evap Monitor-- are two
different systems

Get ALL your OBD Codes & work them one at a time,
& DO NOT Clear any data with code reader or removing
battery cable, or the monitors ALL have to run again

The heater may work in the sensor, but the sensor doesn't
switch fast enough or is worn out & the front sensors get
replaced at 100,000, before they fail or slow down

The Evap Codes will be needed, to work on that issue
That monitor runs last & only every few days

IF--- you had professional scan tool software, you would see
11 monitors & maybe 8 that run on your vehicle

There will be at least 2 for the O2,one for cylinder misfire,
one for evap, one for egr,& three others

My personal suggestion would
be to go for these repair catalogs. I know this website www.reliable-store.com that i used to buy them from, and they sold online it was very good manual. Go ahead, I bet.

You need to find a new shop that can actually diagnose
a vehicles evap system & the emission monitors

You can not do that without professional tools & knowledge

Don't know how many times you need to be told that

The shop you went to isn't doing anything apparently

You have problems to find & resolve & no one else will
give you a different answer, if they even work on vehicles,
or have knowledge of the obd systems & only the pros have
the test equipment needed

You have 8 I/M or Emission Monitors that have to run clear
BEFORE you can go to inspection

Your Catalyst Efficiency comes from the switching comparison
of the front & rear oxygen sensors being out of range

Until you resolve the rear O2 Sensor Heater Issue you won't
know if the cat is good or you have other problems

You need professional scan tool software & a long road test
to even find a problem,then component test,which apparently
wasn't done when they hung the new rear sensor on based on a code

One possible issue is a faulty thermostat. If the engine is not getting up to normal temp the emissions system will not go into closed loop.
I know its hot in Nevada now so thats just a suggestion.
The O2 sensors have heaters to make the exhaust gas hot quick so that the sensors can work.
Is the check engine light coming on - or is it just that the exhaust gas is not hot enough for the test equipment ?

As a rule it takes about 50 miles for the computer to finish it's readiness tests. Some take longer so I would drive it about 75 miles and then check.

Every time you reset the light or disconnect the battery it completely resets the system and it has to go through EVERY test again. The O2, EVAP, and Cat tests are generally the LAST THREE tests that are tested. You're not doing yourself any favors here.

Essentially what these readiness monitors are is the computer's notation that his has run the self diagnostics on each system and that the results feel into the expected results. If it is outside the expected results the computer will generally try to run the test multiple times before setting a DTC and turning on the Check Engine Light. It cannot set the status to "Ready" until it has a successful test within expected results; sometimes multiple successful tests. Sometimes, the tests need to run at different speeds - so the vehicle has to be driven not only at freeway speeds, but also city speeds for the tests to complete properly.

The O2 test MUST complete before the Catalyst test can run. The EVAP test generally requires that you have your fuel level at between 1/4 and 3/4 and that the vehicle sit undisturbed after being driven for a period of time for no less than 8 hours in order to run the EVAP test.

The same can be said for the O2 test sometimes because the computer needs to test the O2 sensors reaction to heating up and cooling down. Eventually they will all complete - unless there is an issue. I have seen where a component was in the process of going out and the computer was getting both GOOD and BAD results when running the tests. As a result it wouldn't set ready status because it wasn't getting the concurrent GOOD test results.

As a Texas Recognized Emissions Repair Facility - my shop sees this kind of stuff all the time.

Good Luck.

the best way to reset it is with a scan tool.
disconnecting the battery for one minute will also remove the code.BUT
if your smog test uses an OBD scan as part of the process,then there will be a problem,because the monitors will not have been set,as they are reset if the battery is disconnected..
most tests allow only one monitor missing,and not the catalyst .
A drive cycle will have to be done to set the monitors.
Typically cold start coolant temp less than 50F,idle for 2 minutes no air condition, accelerate at half throttle to 50mph then drive 3 minutes with a/c on at 50mph steady.decelerate to 10mph without using brakes..Accelerate to 60mph and drive for 5 minutes at steady speed without a/c
deccelerate without braking and drive for 1 minute at 40mph.
stop the car ,use braking.
Shut off the car and add 4 gallons of gas.do not shut off the car for more than 5 minutes.
drive in 3rd gear or overdrive off with rpm 3000 for 1 minute.
decelerate to 10mph.without braking
accelerate to 40 mph in 4th gear.,or overdrive on
decelerate without braking to 10mph.
test complete.
this will set the o2 sensor heater ,o2 sensor,catalyst,evap purge.and the other monitors.

could be your lower O2 sensor