'98 Blazer code 452 repair

[sobtom]

I'm getting a P0452 - Evaporative Emission Control System Pressure Sensor Low Input code reading causing my "service engine soon" light to come on. Does anyone know what this is and how to fix it? Sounds like a bad electrical connection to me.
Thanks

[MT-2500]

Did you leave the gas cap lose or off or fill it up with engine running or run the tank on empty?
Check gas cap and Clear code and see if it comes back.
MT

[sobtom]

Originally Posted by MT-2500

Did you leave the gas cap lose or off or fill it up with engine running or run the tank on empty?
Check gas cap and Clear code and see if it comes back.
MT

I may have filled it up with the engine running, so I'll try your suggestion. It seems to be running rough at times, so I think it might be something else.

[loots-42]

I've had my light on with the P0452 code for about a year now. I replaced the fuel tank pressure sensor and the purge selonoid. Light is still on. damn thing.

[MT-2500]

Loots-42
Time to get it on a scanner and see what is going on. See if tank is holding pressure or vacume.
Get a repair flow chart for that code and go threw the repair chart.
If all wiring and sensor checks out the next and last step is replace pcm.
MT

[sobtom]

Originally Posted by MT-2500

Loots-42
Time to get it on a scanner and see what is going on. See if tank is holding pressure or vacume.
Get a repair flow chart for that code and go threw the repair chart.
If all wiring and sensor checks out the next and last step is replace pcm.
MT

Where do I get a repair flow chart? I'd like to tackle this myself if possible.

[MT-2500]

http://www.alldata.com/products/diy/index.html
Good luck MT

[GMMerlin]

Originally Posted by loots-42

I've had my light on with the P0452 code for about a year now. I replaced the fuel tank pressure sensor and the purge selonoid. Light is still on. damn thing.

Not all SES light activations are caused by a bad componant.
Here is how the system works
The Fuel Tank Pressure Sensor responds to changes in the fuel tank pressure or vacuum. This information is used in order to detect vacuum decay or an excessive vacuum during the EVAP diagnostic routing. The fuel tank pressure sensor signal voltage to the 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.

The Fuel Tank Pressure sensor display on the scan tool has an auto zero feature which occurs at each ignition cycle and is corrected according to the barometric pressure. Because of this, the Fuel Tank Pressure sensor display may not accurately reflect the actual output of the sensor or the conditions within the fuel tank.

Conditions for Running the DTC
The ignition switch is in the RUN position.

Conditions for Setting the DTC
The fuel tank pressure sensor voltage is less than 0.1 volt for more than 5 seconds.

Action Taken When the DTC Sets
The VCM turns ON the MIL after 2 consecutive driving cycles with the fault active.
Here are some things to check first
Check for an open in the 5 V reference circuit.
Check for a short to ground in the 5 V Reference circuit.
Check the 5 V reference circuit for a poor terminal connection at the VCM.
Check the Fuel Tank Pressure Sensor signal for an open or a short to ground.
Check the Fuel Tank Pressure Sensor signal terminal connection at the VCM.
Check the connector at the Fuel Tank Pressure Sensor for:
Salt or water intrusion
Backed out terminals
Improper terminal mating
Poor terminal to wire connections

[sobtom]

Originally Posted by GMMerlin

Not all SES light activations are caused by a bad componant.
Here is how the system works
The Fuel Tank Pressure Sensor responds to changes in the fuel tank pressure or vacuum. This information is used in order to detect vacuum decay or an excessive vacuum during the EVAP diagnostic routing. The fuel tank pressure sensor signal voltage to the 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.

The Fuel Tank Pressure sensor display on the scan tool has an auto zero feature which occurs at each ignition cycle and is corrected according to the barometric pressure. Because of this, the Fuel Tank Pressure sensor display may not accurately reflect the actual output of the sensor or the conditions within the fuel tank.

Conditions for Running the DTC
The ignition switch is in the RUN position.

Conditions for Setting the DTC
The fuel tank pressure sensor voltage is less than 0.1 volt for more than 5 seconds.

Action Taken When the DTC Sets
The VCM turns ON the MIL after 2 consecutive driving cycles with the fault active.
Here are some things to check first
Check for an open in the 5 V reference circuit.
Check for a short to ground in the 5 V Reference circuit.
Check the 5 V reference circuit for a poor terminal connection at the VCM.
Check the Fuel Tank Pressure Sensor signal for an open or a short to ground.
Check the Fuel Tank Pressure Sensor signal terminal connection at the VCM.
Check the connector at the Fuel Tank Pressure Sensor for:
Salt or water intrusion
Backed out terminals
Improper terminal mating
Poor terminal to wire connections

Is the Fuel Tank Pressure Sensor on the top rear of the tank? Do I have to drop the tank down to do the various tests?

[sobtom]

Originally Posted by sobtom

Is the Fuel Tank Pressure Sensor on the top rear of the tank? Do I have to drop the tank down to do the various tests?

Ok, I had the local dealer read the codes and give me an estimate. The computer spit out codes 452 and 440. The dealer recommended a replacement of the fuel tank pressure sensor. Parts: $47 Labor: $400. Needlesstosay, I'll try replacing it myself. Does the tank need to be totally removed? Any other hints? Thanks.

[loots-42]

Originally Posted by sobtom

Ok, I had the local dealer read the codes and give me an estimate. The computer spit out codes 452 and 440. The dealer recommended a replacement of the fuel tank pressure sensor. Parts: $47 Labor: $400. Needlesstosay, I'll try replacing it myself. Does the tank need to be totally removed? Any other hints? Thanks.

I was able to change mine on my 98 Jimmy without dropping the tank. Dropped the spare tire, jacked the backend up and was able to reach up above the tank and replace. I'm 6'3" and have long arms.

Let us know if that fixes yours. It didn't fix my 452. I also change the purge selonoid. Code still prevails. Dealer just told be it would be $225 to do the diagnosis.

[sobtom]

Originally Posted by loots-42

I was able to change mine on my 98 Jimmy without dropping the tank. Dropped the spare tire, jacked the backend up and was able to reach up above the tank and replace. I'm 6'3" and have long arms.

Let us know if that fixes yours. It didn't fix my 452. I also change the purge selonoid. Code still prevails. Dealer just told be it would be $225 to do the diagnosis.

The fee for diagnosis for me was $70 a good deal I guess. I'll get on this project this weekend and see what happens. It certainly would be a plus if I can do it without dropping the tank.....

[loots42]

I still have the 452 code. I believe thats low pressure. Does anyone know where the vacuum pressure source is? Maybe there's not enough vacuum being put on the tank?