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Thread: DTC 33 - EGR Control Pressure/Baro Sensor Circuit High

  1. #1
    Join Date
    Nov 2007
    Location
    Phoenix, AZ USA
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    6

    Default DTC 33 - EGR Control Pressure/Baro Sensor Circuit High

    Can anyone tell me what this code means and how to resolve/troubleshoot it? I have a 94 Blazer 6.5L i just put a new "used" PMD on it and this is the code that it is throwing. I replaced the Intake with a non-EGR intake and sealed of the rubber hose but I still receiving this code.

    Thanks.
    1994 Chevy Blazer 6.5TD

  2. #2
    Join Date
    Feb 2007
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    Baja California Sur Mexico
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    Disconnect the tube to the sensor and block the tube, there is vacuum in the tube when there shouldn't be.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban "F" VIN #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

  3. #3
    Join Date
    Dec 2007
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    Actually, youre getting a low vacuum code, which means you need the hose hooked up to the sensor, because you still have the S L56 engine computer chip. If you get an F L65 chip it would not throw those codes.

    To get rid of the code make sure the sensor does have the vacuum plugged in and that vacuum is getting to the solenoid on the valve cover.
    1994 GMC ext cab long bed C1500 6.5TD w/ 50 gallon aux fuel tank/tool box; 480LE; 3.42 gears; Engh Motors L65 Power E-PROM and OBDI GMTDScan; 3.5" exhaust (until I fix that); SSDS FSD Heatsink, Intake, Marine Injectors and fan upgrade; Boost, EGT, Trans Temp guages; 84K original miles

  4. #4
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    Nov 2007
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    Phoenix, AZ USA
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    Where is the sensor? Does any one have pictures of what I should do?
    1994 Chevy Blazer 6.5TD

  5. #5
    Join Date
    Feb 2007
    Location
    Baja California Sur Mexico
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    Buddy is right, it is a low vacuum code, 31 is for high vacuum. Did you block the hose that came off the top of the intake? That is the one to block. The EGR solenoid needs to be functioning to prevent a 31 or 33 code.
    Grant H.
    1995 6.5 turbo GMC K2500 extra cab 4x4 pickup, PMD under bumper, mechanical wastegate, 228,000 miles, rebuilt engine, 4.10 diff, 16 mpg
    1994 6.5 turbo GMC K2500 4x4 suburban "F" VIN #9 resistor, PMD in the bumper, mechanical waste gate, 226,000 miles, Positrac 3.73 diff, 17 mpg highway.
    1982 4x4 shortbed 6.2 Chev 260,000 miles untouched motor 17 MPG 4.27 diff. Best thing I ever owned, 21 years.

  6. #6
    Join Date
    Dec 2007
    Posts
    444

    Default

    So you learned enough to delete the EGR, but not the corresponding systems.

    The sensor is on the firewall drivers side. Looks a lot like the MAP boost sensor thats on the intake. There should be a vacuum hose to it, and if not that is why you get the code. The vacuum hose should travel from the solenoid cluster that is or was on your drivers side valve cover.

    The sponsors store has pictures of the sensors, this is the EGR/BARO sensor. you cannot get rid of it either, it is necessary even if you dont have EGR.
    1994 GMC ext cab long bed C1500 6.5TD w/ 50 gallon aux fuel tank/tool box; 480LE; 3.42 gears; Engh Motors L65 Power E-PROM and OBDI GMTDScan; 3.5" exhaust (until I fix that); SSDS FSD Heatsink, Intake, Marine Injectors and fan upgrade; Boost, EGT, Trans Temp guages; 84K original miles

  7. #7
    Join Date
    Mar 2007
    Location
    Near Clifton, Illinois
    Posts
    7

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    For the 1995 Tahoe

    12569240 is the EGR Baro sensor - verified

    The waste gate solenoid is GM 1997255 - verified

    The EGR solenoids - vacuum regulator valves EGR SOL VLV (vent) & EGR SOL VLV (PWM) have 2 different numbers, but I do not know which is which.

    1997225 & 1997226

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