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2001 Suburban 1500 4WD has P0452 code

Discussion in 'Chevy Suburban Forum (GMC Yukon XL)' started by Space Ace, Nov 8, 2013.

  1. Space Ace

    Space Ace New Member

    I have a 2001 Chevy Suburban 1500 4WD. About a year and half ago I dropped the gas tank to replace the fuel pump unit. I got the new unit (FTPS included) and finished the job. About 2 months after that job I got OBDII code of P0452 (Evaporative Emission Control System Pressure Sensor Low Input), it would not erase, but since it didn't affect the engine, I did not mess with it. Now it is time to inspect and of course it will not pass emmisions. Usually the P0452 code appears twice when I scan the system after a few weeks, but sometimes a P0453 code gets thrown up (same as other but high input at the FTPS). The FTPS is on top of tank and in order to check or replace I need to drop tank again (don't want to do it, if I don't have too). The other potensial components could be the canister, itself or the vent solenoid or purge solenoid or any of the hoses.
    When the P0452 code is thrown is it almost always a bad or badly connected FTPS?
    Any help or tips would be greatly appreciated!
  2. mfleetwood

    mfleetwood Rockstar 4 Years ROTM Winner 5000 Posts

    This may help you a little bit. You can use a voltmeter to diagnose a couple of possibilities. I highlighted below in the bold font. Unfortunately, I think you are correct as it appears you need to remove your fuel tank unless you can reach it somehow to make a connection (I'm not that familiar with your vehicle).
    __________________________________________________________________________________
    P0453 - Evaporative Emissions Control System Pressure Sensor High Input OBD-II Trouble Code Technical Description Evaporative Emissions Control System Pressure Sensor High Input

    *What does that mean? The EVAP (Evaporative Emissions) System allows fuel tank vapors to be purged into the engine and burnt rather than expelled into the atmosphere as harmful emissions. The EVAP system contains a pressure sensor to check the integrity of the system. Periodically, the EVAP system performs a pressure test to check that there are no leaks in the system. It uses this sensor, also known as a fuel tank pressure (FTP) sensor to check for leaks. Basically P0453 means the PCM (Powertrain Control Module) noticed the EVAP Pressure sensor or FTP is indicating a higher than normal pressure (above 4.5 Volts) in the EVAP system. NOTE: On some vehicles the FTP is a part of the fuel pump assembly in the tank.

    *Potential Symptoms: There will likely be no noticeable symptoms along with this code other than the MIL (Malfunction Indicator Lamp), commonly known as Check Engine Light illumination. However, there may be noticeable fuel odors in some cases.

    *Causes: A P0453 DTC trouble code may be caused by one or more of the following: Open on FTP sensor signal wire Short to voltage on FTP sensor signal wire Bad FTP sensor Abnormally high pressure in fuel tank due to blockage in EVAP purge hoses or overfilled tank Loose/damaged FTP sensor connector Loss of ground to the sensor

    *Possible Solutions: Using an scan tool access FTP sensor value with Key on Engine off (KOEO). Normal value is usually somewhere near 2.5 Volts at atmospheric pressure (may fluctuate some due to altitude). It shouldn't ever be above 4.5 Volts.
    1) If it is close to 2.7V with the gas cap off, the problem is likely intermittent. Using a Digital Volt Ohm Meter, measure the voltage on the signal wire while trying to induce the problem by wiggle testing all the wiring at the FTP sensor. If the voltage fluctuates when wiggle testing, check for connector problems; i.e. water in the connector, broken or chafed wiring.
    2) If the value shown on the scan tool is above 4.5V, unplug the sensor (if possible) and check for voltage again. If the high voltage is still present when unplugged, inspect wiring harness for a short to voltage on the signal wire. If the high voltage disappears when unplugging the sensor, check for a good ground to the sensor and proper reference voltage. If you have a good ground and 5 Volts reference voltage, replace the FTP sensor since it's likely shorted out.

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