I live in Oregon, and have a 1998 chevy blazer (2WD).I recently took it the DEQ to get new tags, but upon inspection, they noticed my check engine light was on, so I didn't pass, and they handed me a paper that said, " P0452 Evaporative Emission Control System Pressure Sensor Low Input. What do I do?

Double check the what they told you the code was... there is no P0452 for that year vehicle.
Unless you posted the incorrect year, or the incorrect code...

THe previous comment about P0452 not being valid for 1998 seems to be incorrect. My 1998 GMC Jimmy (same as Blazer) is showing P0452 as well. It started soon after fuel pump and gas tank was replaced. When reset the code comes back again after one or two short drives. Any idea why this is happening? Where do I find the Evaporative Emission Control System Pressure Sensor on this vehicle?

The pressure sensor is mounted on the top of the tank. If during service, that sensor or harness was damaged, you can get that code.
If you don't find any obvious damage to the harness or connector, you will need a scan tool to monitor data while moving the harness.
If the harness is OK, replace the sensor.
The Fuel Tank Pressure (FTP) Sensor responds to changes in the fuel tank pressure or vacuum. The fuel tank pressure sensor signal voltage to the Vehicle Control Module (VCM) varies from a minimum of about 0.1 volts with pressure in the fuel tank to above 4.0 volts with a high vacuum in the fuel tank.

Quote:

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Originally Posted by CaptainRich

The pressure sensor is mounted on the top of the tank. If during service, that sensor or harness was damaged, you can get that code.
If you don't find any obvious damage to the harness or connector, you will need a scan tool to monitor data while moving the harness.
If the harness is ok, replace the sensor.
The Fuel Tank Pressure (FTP) Sensor responds to changes in the fuel tank pressure or vacuum. The fuel tank pressure sensor signal voltage to the Vehicle Control Module (VCM) varies from a minimum of about 0.1 volts with pressure in the fuel tank to above 4.0 volts with a high vacuum in the fuel tank.

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Do I have to drop the tank to easily get at the sensor? Is there an easy way to locate a leak in the tank that may cause this code?

Yes, the tank has to come at least part-way down just to get a hand on the sensor.
There isn't a quick way to diagnose your evap system.
One thing I'd double check is the gas cap. Is it an original and what is the condition of the O-ring seal? You may want to replace the cap/seal if it hasn't been done recently (in the last year or two), then see if that code goes away.

Yes I just had the same code on a 1999 Chev Blazer!I just change the fuel pump on it! But the code keeps coming back

Where is the evaporative emission control system pressure sensor low located on a 1999 chevrolet sliverdo truck

Where is the evaporative emission control system pressure sensor low located on a 1999 chevrolet sliverdo truck

ftp sender is almost always going to be located somewhere on the fuel pressure sender, more often than not it is better just to replace the entire sending unit assembly just because it is submerged under fuel constantly, and by the time the fuel tank pressure sender goes bad the rest is usually on it's way.

Another thought for those who were testing everything and the electronics were testing good, maybe the stick is just that, a stick (maybe you really do have a high pressure under those specific running conditions that tripped the sensor, but once the car is back to idle, or off it doesn't, which may lead me to think a possible evap vent solenoid or vent circuit error, or even maybe a clogged vent line on the sending unit?)

Usually when you get any kind of code that has to do with the EVAP system, it is a vacuum leak somewhere. Not always, 98% of the time this is what is causing it. So check all vacuum hoses first. It is pretty cheap just to replace them all. If you have a hand held vacuum pump you can check all the lines with that. The EVAP System has to do with the recirculation of the gas fumes to let the motor burn them for fuel.

On my 1999 chevy blazer (2WD) it turn out I had to replace my gas cap . On my car where the gas tank is there is a Canister Vent Valve Solenoid. That was not working at all . Making my light come on . The Canister Vent Valve Solenoid is in the back of the chevy blazer on the diver side .

Hi
One of the main reasons for this code is a leak in the fuel tank.

Vapour can escape, could be a leaking fuel cap, or pump / sender seal not sealing.

You can smoke test the through the service port of the evap system, normally green in colour located in the engine bay.

Hope this helps

Tim