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'97 Pontiac Transport/Montana 3.4L V-6. How do I test the fuel EVAP vacuum switch--EVS. It is on a sled 1 from the Canister Purge-CP Solenoid valve. CP checks out. EVS has a 2-wire harness.

How do you test a fuel EVAP vacuum Switch? I have energized the EVS with 5V then 12V the valve remains stuck? open. Does it simply make an electrical connection internally competing the circuit back to the PCM under vacuum situations? It's a 2-wire unit both have been removed to bench test.

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You need to have a full function live data GM OBD2 scanner.

Posted on May 18, 2017

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2007. What are the probable causes of DTC P0446?


DTC P0446: Evaporative Emissions (EVAP) Vent System Performance
Circuit/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 valve Open and the EVAP canister vent solenoid valve 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 valve Closed and the EVAP canister vent solenoid valve 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 inch H2O in a calibrated time, this DTC sets.
Diagnostic Aids
?€¢
An intermittent condition could be caused by a damaged EVAP vent housing, a temporary blockage at the EVAP canister vent solenoid valve inlet, or a pinched vent hose. A blockage in the vent system will also cause a poor fuel fill problem.


?€¢
An EVAP canister, vent hose, or vent solenoid valve that has restricted flow may cause this DTC to set. Using a purge solenoid command with a scan tool will allow vacuum to be applied to the system instead of pressure. With the engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 5 inches H2O.


?€¢
An EVAP canister filter that is restricted can cause this DTC to set. Refer to Evaporative Emission Canister Replacement .


?€¢
Disconnecting one component at a time while the EVAP system is under flow will help to pinpoint a restriction in the system


Do you have a scan tool that reads data PID'S ?
Your FTP - fuel tank pressure sensor could be at fault !

    Ignition ON and fuel cap removed, verify that the FTP sensor parameter is between 1.3-1.7 volts. ?‡'
    If not within the specified range, go to the FTP sensor section in Circuit/System Testing.

  1. Install the fuel cap.
  2. With the engine running, the EVAP canister vent solenoid valve open, and the EVAP canister purge solenoid valve commanded to 100 percent, the fuel tank vacuum should not increase to more than 12 inches H2O.
?‡'
If the fuel tank vacuum is greater than the specified range, go to the restriction section in Circuit/System Testing.



If

Sep 06, 2015 | Chevrolet Impala Cars & Trucks

1 Answer

How do I repl the vent solenoid on my 2007 trailblazer 6 cyl. I believe it is located on charcoal canister


Sorry you wasted your money on parts you didn't need ! There is a very specific diagnostic flow to testing this DTC - diagnostic trouble code ! An tools needed , scan tool , vacuum gauge ! the vent solenoid has nothing to do with this code .
Connector End View Reference: Powertrain Control Module Connector End Views or Engine Controls Connector End Views

1

Did you perform the Diagnostic System Check - Vehicle?
--
Go to Step 2
Go to Diagnostic System Check - Vehicle

2
  1. Disconnect the purge pipe from the evaporative emission (EVAP) canister purge solenoid valve.
  2. Install a hand held vacuum gage to the EVAP canister purge solenoid valve purge port.
  3. Disconnect the EVAP canister purge solenoid valve harness connector.
  4. Monitor vacuum on the vacuum gage.
  5. Start the engine and allow the engine to idle.
  6. Increase the idle to 1,200-1,500 RPM.
Does the vacuum gage indicate an increase in vacuum?
--
Go to Step 8
Go to Step 3

3

  1. Connect the EVAP canister purge solenoid valve harness connector.
  2. Monitor vacuum on the vacuum gage.
  3. Increase the idle to 1,200-1,500 RPM.
Does the vacuum gage indicate an increase in vacuum?
--
Go to Step 5
Go to Step 4

4
  1. Turn OFF the ignition.
  2. Remove and then install the fuel fill cap.
  3. Turn ON the ignition, with the engine OFF.
  4. Observe the Fuel Tank Pressure Sensor parameter with a scan tool.
Is the Fuel Tank Pressure Sensor parameter within the specified value?
-0.5 to +0.5 in H2O
Go to Diagnostic Aids
Go to Step 6

5

Test the control circuit of the EVAP canister purge solenoid valve for a short to ground. Refer to Testing for Short to Ground and Wiring Repairs.
Did you find and correct the conditions?
--
Go to Step 9
Go to Step 8

6

Test for an intermittent and for a poor connection at the fuel tank pressure (FTP) sensor. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs.
Did you find and correct the condition?
--
Go to Step 9
Go to Step 7

7

Replace the FTP sensor. Refer to Fuel Tank Pressure Sensor Replacement .
Did you complete the replacement?
--
Go to Step 9
--

8

Replace the EVAP canister purge solenoid valve. Refer to Evaporative Emission Canister Purge Solenoid Valve Replacement .
Did you complete the replacement?
--
Go to Step 9
--

9

  1. Clear the DTCs with a scan tool.
  2. Turn OFF the ignition for 30 seconds.
  3. Start the engine.
  4. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?
--
Go to Step 2
Go to Step 10

10

Observe the Capture Info with a scan tool.
Are there any DTCs that have not been diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List - Vehicle
System OK

Feb 28, 2015 | 2007 Chevrolet Trailblazer

1 Answer

Po441 2002 Hyundai, engine hard starting after fill up


Most likely is a bad EVAP purge valve. But check below list.
This indicates that a part of the EVAP control system is no longer functioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle'sicon1.png fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

EVAP emission canister purge is controlled by a valve which allows engine vacuum to pull stored fuel vapors from fuel tank into the engine to be burned, rather than be vented to atmosphere. A vacuum switch is used to detect when flow exists. If the PCM commands purge and sees that the switch is closed (indicating no detected purge flow) P0441 is set.
FB.init("dd7d9e9681341cde77587bc6a2029f6f"); OBD-Codes.com on Facebook Symptoms

Likely, no symptoms will be discernible to the driver, other than the illuminated Check Engine Light.
Causes

A code P0441 could mean one or more of the following has happened:

  • Bad vacuum switch
  • Broken or damaged EVAP line or canister
  • Open in PCM purge command circuit
  • Open or short in Voltage feed circuit to Purge Solenoid
  • Faulty purge solenoid
  • Restriction in EVAP solenoid, line or canister
  • Corrosion or resistance in purge connector
  • Bad PCM
Possible Solutions

With a P0441 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:

  • Replace Leak Detection Pump / LDP
  • Repair damaged EVAP lines or canister
  • Repair open or short in voltage feed circuit to Purge Solenoid
  • Repair open in PCM purge command circuit
  • Replace purge Solenoid
  • Replace vacuum switch
  • Repair restriction in Evap line or canister or solenoid
  • Repair resistance in purge connector
  • Replace PCM

Oct 24, 2012 | Hyundai Elantra Cars & Trucks

1 Answer

Failed smog test Code PO443 ck. engine light on


This is the generic definition for the code.
Your year and model may be different. Possible causes include a faulty purge control valve or the circuit back to the computer.

P0443 Description The Evaporative Emission System (EVAP) canister purge volume control solenoid valve uses a ON/OFF duty to control the flow rate of fuel vapor from the EVAP canister. The EVAP canister purge volume control solenoid valve is moved by ON/OFF pulses from the Engine Control Module (ECM). The longer the ON pulse, the greater the amount of fuel vapor that will flow through the valve.
Read more: http://engine-codes.com/p0443.html#ixzz27RdAClP2

Sep 24, 2012 | 2000 Pontiac Montana

1 Answer

How do I resolve diagnostic code P0455 on my 2005 Chevrolet Tahoe?


Here is the definition and possible causes.

Possible causes - Missing or loose fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- EVAP canister or fuel tank leaks
- EVAP system hose leaking
- Fuel tank leaking
P0455 CHEVROLET Description This diagnosis detects leaks in the Evaporative Emission System (EVAP) purge line using engine intake manifold vacuum. If pressure does not increase, the Engine Control Module (ECM) will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition.


The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.
Read more: http://engine-codes.com/p0455_chevrolet.html#ixzz24fVfq0Bx

Aug 26, 2012 | 2005 Chevrolet Tahoe

1 Answer

P0446 ford escort 98


This Pinpoint Test is intended to diagnose the following:
  • Canister vent (CV) solenoid (9F945) (electrical concern only)
  • Fuel filler cap (9030)
  • Fuel tank pressure (FTP) sensor (9C052)
  • EVAP canister tube (fuel tank to EVAP canister)(9A228)
  • Fuel canister purge outlet tube (EVAP canister to EVAP canister purge valve) (9D661)
  • EVAP return tube (EVAP canister purge valve to intake manifold) (9G271)
  • EVAP canister purge valve (9C915)
  • Vacuum source line (input port vacuum to intake manifold)
  • Harness circuits: CV, FLI, FTP, EVAP Canister Purge Valve, SIG RTN, vehicle power (VPWR), reference voltage (VREF) and power ground (PWR GND)
  • Powertrain control module (PCM) (12A650)
This Pinpoint Test is used as an assistance in diagnosing the following EVAP components:
  • EVAP canister and bracket assembly (9E857)
    • EVAP canister sleeve assembly (fitting)(9D925)
    • Canister vent (CV) solenoid - hose assembly (9F976 or 9K318)
    • EVAP canister (9D653)
    • Canister vent (CV) solenoid (9F945)(mechanical concern only)
  • Fill limit valve assembly (9A086)
  • Fuel filler pipe flapper valve (9B085)
  • Fuel filler pipe check valve (9189), assembly (9285)
  • Fuel tank filler pipe (9034)
  • Fuel tank assembly (with fuel vapor vent valve) (9K007)
  • Fuel tank assembly (without fuel vapor vent valve) (9002)
  • Fuel vapor control valve (9B190)
  • Fuel vapor vent valve (9B593)
  • Liquid/vapor fuel discriminator (9G332)
  • On-board refueling vapor recovery (ORVR) T - connector assembly (9S314)
Description For additional information on the Evaporative Emission (EVAP) System, refer to Section 1A .
For additional information on the Evaporative Emission System Monitor, refer to Section 1A .
Pinpoint Test Schematics Escort/Tracer (2V)
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May 28, 2011 | 1998 Ford Escort

3 Answers

What is evaporation control system malfuction mean? The code is P0440


Hi, the computer has sensed through the fuel tank pressure sensor that the vapor cannister is not evacuating properly. I have pasted details on the EVAP system below. Check the purge valve on top of the engine as shown below (#1 in picture). Make sure the electrical connector is on the valve, that the wires are not damaged, and check the hose for kinks. If all looks good, I recommend you replace the valve. A new valve is $23 at autozone. Please let me know if you have more questions and thanks for using FixYa.

jturcotte_1020.gifjturcotte_260.jpg
Description & Operation
EVAP Canister
The canister is filled with carbon pellets used to absorb and store fuel vapors. Fuel vapor is stored in the canister until the control module determines that the vapor can be consumed in the normal combustion process.
EVAP Control System
The evaporative emission (EVAP) control system limits fuel vapors from escaping into the atmosphere. Fuel tank vapors are allowed to move from the fuel tank, due to pressure in the tank, through the vapor pipe, into the EVAP canister. Carbon in the canister absorbs and stores the fuel vapors. Excess pressure is vented through the vent line and EVAP vent solenoid to atmosphere.
The EVAP canister stores the fuel vapors until the engine is able to use them. At an appropriate time, the control module will command the EVAP purge solenoid ON, open, allowing engine vacuum to be applied to the EVAP canister. With the EVAP vent solenoid OFF, open, fresh air will be drawn through the solenoid and vent line to the EVAP canister. Fresh air is drawn through the canister, pulling fuel vapors from the carbon.
The air/fuel vapor mixture continues through the EVAP purge pipe and EVAP purge solenoid into the intake manifold to be consumed during normal combustion. The control module uses several tests to determine if the EVAP system is leaking.
The EVAP system consists of the following components:
EVAP Purge Solenoid
The EVAP purge solenoid controls the flow of vapors from the EVAP system to the intake manifold. This normally closed solenoid is pulse width modulated (PWM) by the control module to precisely control the flow of fuel vapor to the engine. The solenoid will also be opened during some portions of the EVAP testing, allowing engine vacuum to enter the EVAP system.
EVAP Service Port
The EVAP service port is located in the EVAP purge pipe between the EVAP purge solenoid and the EVAP canister. The service port is identified by a green colored cap.
EVAP Vent Solenoid
The EVAP vent solenoid controls fresh airflow into the EVAP canister. The solenoid is normally open. The control module will command the solenoid closed during some EVAP tests, allowing the system to be tested for leaks.
Fuel Tank Pressure Sensor
The FTP sensor measures the difference between the pressure or vacuum in the fuel tank and outside air pressure. The control module provides a 5-volt reference and a ground to the FTP sensor. The FTP sensor provides a signal voltage back to the control module that can vary between 0.1-4.9 volts. As FTP increases, FTP sensor voltage decreases, high pressure = low voltage. As FTP decreases, FTP voltage increases, low pressure or vacuum = high voltage.

Feb 10, 2011 | 2002 Chevrolet TrailBlazer

1 Answer

Po 442 po 455


P0442 - Evaporative Emissions System Leak Detected (Small Leak)

P0455 - Evaporative Emissions System Leak Detected (Gross Leak)

This diagnosis detects leaks in the EVAP purge line using engine intake manifold vacuum. If pressure does not increase, the ECM will check for leaks in the line between the fuel tank and EVAP canister purge volume control solenoid valve under the following vacuum test condition. The vacuum cut valve bypass valve is opened to clear the line between the fuel tank and the EVAP canister purge volume control solenoid valve. The EVAP canister vent control valve will then be closed to shut the EVAP purge line off. The EVAP canister purge volume control solenoid valve is opened to depressurize the EVAP purge line using intake manifold vacuum. After this depressurization is implemented, the EVAP canister purge volume control solenoid valve will be closed.

Causes:
- Missing Fuel cap
- Incorrect fuel filler cap used
- Fuel filler cap remains open or fails to close
- Foreign matter caught in fuel filler cap
- Incorrect fuel tank vacuum relief valve
- Leak is in line between intake manifold

Solutions:
- Re-tighten or replace fuel tank filler cap
- Replace damaged or leaking EVAP canister
- Replace damaged or leaking lines.

Feb 10, 2011 | Chrysler Town and Country Cars & Trucks

1 Answer

1996 saab 900s p0441 evaporative emission system incorrect purge flow


This indicates that a part of the EVAP control system is no longer fuctioning correctly. The EVAP system consists of many parts, including (but not limited to) the gas cap, fuel lines, carbon canister, purge valve, and other hoses. The (EVAP) emission control system prevents the escape of fuel vapors from a vehicle's fuel system. Fuel vapors are routed by hoses to a charcoal canister for storage. Later, when the engine is running a purge control valve opens allowing intake vacuum to siphon the fuel vapors into the engine.

EVAP emission canister purge is contolled by a valve which allows engine vacuum to pull stored fuel vapors from fuel tank into the engine to be burned, rather than be vented to atmosphere. A vacuum switch is used to detect when flow exists. If the PCM commands purge and sees that the switch is closed (indicating no detected purge flow) P0441 is set.

Causes: A code P0441 could mean one or more of the following has happened:
* Bad vacuum switch
* Broken or damaged EVAP line or canister
* Open in PCM purge command circuit
* Open or short in Voltage feed circuit to Purge Solenoid
* Faulty purge solenoid
* Restriction in EVAP solenoid, line or canister
* Corrosion or resistance in purge connector
* Bad PCM

Possible Solutions: With a P0441 OBD-II trouble code, diagnosis can be tricky at times. Here are some things to try:
* Common Chrysler fix - Replace Leak Detection Pump / LDP
* Repair damaged EVAP lines or canister
* Repair open or short in voltage feed circuit to Purge Solenoid
* Repair open in PCM purge command circuit
* Replace purge Solenoid
* Replace vacuum switch
* Repair restriction in Evap line or canister or soleniod
* Repair resistance in purge connector
* Replace PCM

Test it and tel us news.

Jan 11, 2011 | 1996 Saab 900

1 Answer

I had an emission test done on my 98 bonneville and it failed because code P0440 evap control system what should i do ?


Here's list why your car is coming up with this code. It could be any of these things causing it.
DTC detecting condition:
  • EVAP control system has a leak.
  • EVAP control system does not operate properly.
Possible cause:
  • Incorrect fuel tank vacuum relief valve
  • Incorrect fuel filler cap used
  • Fuel filler cap remains open or fails to close.
  • Foreign matter caught in fuel filler cap.
  • Leak is in line between intake manifold and EVAP canister purge volume control solenoid valve.
  • Foreign matter caught in EVAP canister vent control valve.
  • EVAP canister or fuel tank leaks
  • EVAP purge line (pipe and rubber tube) leaks
  • EVAP purge line rubber tube bent
  • Blocked or bent rubber tube to EVAP control system pressure sensor
  • Loose or disconnected rubber tube
  • EVAP canister vent control valve and the circuit
  • EVAP canister purge volume control solenoid valve
  • EVAP canister purge volume control solenoid valve and the circuit
  • Absolute pressure sensor
  • Fuel tank temperature sensor
  • O-ring of EVAP canister vent control valve is missing or damaged
  • Water separator
  • EVAP canister is saturated with water
  • EVAP control system pressure sensor
  • Refueling control valve
  • ORVR system leaks
  • Fuel level sensor and the circuit

Apr 01, 2010 | 1998 Pontiac Bonneville

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