fxmfrank Posted January 19, 2012 Report Share Posted January 19, 2012 I have been wrestling with a P0446 Code (EVAP Circuit Malfunction) on my 2002 Cadillac Deville. I have made several corrections but no success in eliminating the code permanently (code returns after 4 or 5 days). I replaced Fuel Tank Pressure Sensor, Canister evap solenoid, and evap purge solenoid. Checked all hoses and canister for blockage. I've been told that in order for the test to run and reset the code the gas tank level must be between 1/4 and 3/4 full and run at highway speed (55 mph for 3 minutes and reduce speed to 20 mph without braking). My problem is that my fuel level sending unit does not work and it indicates the fuel tank is full all the time. Should probably replace it eventually. So now it sounds like I can not reset the code because the test won't run due to the fuel level appearing to be at full. Can anyone help me with this? . Link to comment Share on other sites More sharing options...
Ranger Posted January 20, 2012 Report Share Posted January 20, 2012 Have you manually cleared the code? Checked all hoses and canister for blockage. Blockage is not the problem. It's usually a vacuum leak. Link to comment Share on other sites More sharing options...
fxmfrank Posted January 20, 2012 Author Report Share Posted January 20, 2012 I cleared the code and waiting to see if it comes back. However, I was told by a GM mechanic that the fuel level needs to be between 1/4 to 3/4 full in order to have the test and reset procedure take place. My fuel lever gauge hasn't worked for awhile so the feeling is it won't recognize the required fuel level in the tank. Link to comment Share on other sites More sharing options...
fxmfrank Posted January 21, 2012 Author Report Share Posted January 21, 2012 Is it Fact or Fiction: Fuel Tank must be between 1/4 and 3/4 full in order for a DTC to be erased from the computer memory on GM cars, specifically 2002 Cadillac Deville. If anyone can give me a quick answer, like yes, no or never heard of that. Trying to decide if I should replace my Fuel Level Sending unit immediately or at a later date. Thanks everyone!!! Sorry I left out the most important item. Talking about a P0446 code (EVAP Emission Control System Vent Circuit Malfunction) Link to comment Share on other sites More sharing options...
BodybyFisher Posted January 21, 2012 Report Share Posted January 21, 2012 I would say NO, in order for the DTC code P0446 to be set after a test, the fuel level must be between 15 and 85% see highlight below, maybe that is what you are hearing. If your fuel level sensor is causing a full tank to register, unless its intermitting, this code probably would not set. DTC P0446 System Description This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid Open and the EVAP canister vent solenoid Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid Closed and the EVAP canister vent solenoid Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets. Conditions for Running the DTC </h5> DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0440, P0442, P0443, P0449, P0452, P0453, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122 are not set. The ignition voltage is between 10-18 volts. The barometric pressure (BARO) is more than 75 kPa. The fuel level is between 15-85 percent. The start-up engine coolant temperature (ECT) is less 30°C (86°F). The intake air temperature (IAT) is between 4-30°C (39-86°F). The start-up ECT and IAT are within 9°C (16°F) of each other. The vehicle speed sensor (VSS) is less than 121 km/h (75 mph). Conditions for Setting the DTC The FTP (Fuel Tank Pressure) does not increase a calibrated amount during a calibrated period of time. Action Taken When the DTC Sets </h5> The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. Conditions for Clearing the MIL/DTC </h5> The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. A current DTC, Last Test Failed, clears when the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. Clear the MIL and the DTC with a scan tool. Diagnostic Aids <h5></h5> An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent solenoid inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem. Pre-1995 - DTC codes OBD1 >> 1996 and newer - DTC codes OBD2 >> https://www.obd-codes.com/trouble_codes/gm/obd_codes.htm How to check for codes Caddyinfo How To Technical Archive >> http://www.caddyinfo.com/wordpress/cadillac-how-to-faq/ Cadillac History & Specifications Year by Year http://www.motorera.com/cadillac/index.htm Link to comment Share on other sites More sharing options...
Texas Jim Posted January 21, 2012 Report Share Posted January 21, 2012 Is it Fact or Fiction: Fuel Tank must be between 1/4 and 3/4 full in order for a DTC to be erased from the computer memory on GM cars, specifically 2002 Cadillac Deville. If anyone can give me a quick answer, like yes, no or never heard of that. Trying to decide if I should replace my Fuel Level Sending unit immediately or at a later date. Thanks everyone!!! Sorry I left out the most important item. Talking about a P0446 code (EVAP Emission Control System Vent Circuit Malfunction) The codes can be cleared from the DIC... Link to comment Share on other sites More sharing options...
fxmfrank Posted January 21, 2012 Author Report Share Posted January 21, 2012 I would say NO, in order for the DTC code P0446 to be set after a test, the fuel level must be between 15 and 85% see highlight below, maybe that is what you are hearing. If your fuel level sensor is causing a full tank to register, unless its intermitting, this code probably would not set. DTC P0446 System Description This DTC tests the evaporative emission (EVAP) system for a restricted or blocked EVAP vent path. The control module commands the EVAP canister purge solenoid Open and the EVAP canister vent solenoid Closed. This allows vacuum to be applied to the EVAP system. Once a calibrated vacuum level has been reached, the control module commands the EVAP canister purge solenoid Closed and the EVAP canister vent solenoid Open. The control module monitors the fuel tank pressure (FTP) sensor for a decrease in vacuum. If the vacuum does not decrease to near 0 inches H2O in a calibrated time, this DTC sets. Conditions for Running the DTC </h5> DTCs P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0121, P0122, P0123, P0125, P0440, P0442, P0443, P0449, P0452, P0453, P1106, P1107, P1111, P1112, P1114, P1115, P1121, P1122 are not set. The ignition voltage is between 10-18 volts. The barometric pressure (BARO) is more than 75 kPa. The fuel level is between 15-85 percent. The start-up engine coolant temperature (ECT) is less 30°C (86°F). The intake air temperature (IAT) is between 4-30°C (39-86°F). The start-up ECT and IAT are within 9°C (16°F) of each other. The vehicle speed sensor (VSS) is less than 121 km/h (75 mph). Conditions for Setting the DTC The FTP (Fuel Tank Pressure) does not increase a calibrated amount during a calibrated period of time. Action Taken When the DTC Sets </h5> The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails. The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records. Conditions for Clearing the MIL/DTC </h5> The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail. A current DTC, Last Test Failed, clears when the diagnostic runs and passes. A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic. Clear the MIL and the DTC with a scan tool. Diagnostic Aids <h5></h5> An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP vent solenoid inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem. Link to comment Share on other sites More sharing options...
fxmfrank Posted January 21, 2012 Author Report Share Posted January 21, 2012 Thanks! I guess I need to replace fuel level sensor now. The good news its accessible from the trunk, don't have to drop the tank. One more question should I just replace the fuel level sensor or the fuel pump as well? I'd rather not fool with the fuel pump seeing that it works fine. Looks like detaching the fuel level sensor from the fuel pump isn't very difficult. Link to comment Share on other sites More sharing options...
Ranger Posted January 22, 2012 Report Share Posted January 22, 2012 Frank, Before you replace anything, check with your dealer. I can't swear to it but I think there may have been a recall on that FTP sensor and it is possible that you may be able to get it replaced for free. Oops! Disregard. Just reread this thread and realized that you already replaced it and are now talking about the level sensor and pump. The pump is a crap shoot. May last forever or it may go out tomorrow. Choice is yours. Link to comment Share on other sites More sharing options...
fxmfrank Posted January 22, 2012 Author Report Share Posted January 22, 2012 Thanks Ranger! Ya, it was a recall back in 2003. I didn't think it was worth going to the dealer on the FTP sensor, especially with the P0446 code. I probably would have paid a small fortune before I got out. The FTP Sensor cost about $37. at Advance Auto Parts and took about 10 minutes to install. I think I'll just go with the fuel level sensor and deal with the fuel pump when needed. In either case, I need to pull the fuel pump to get at the fuel level sensor. Link to comment Share on other sites More sharing options...
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