I have a small vacuum leak in evaporative system , please help, where is a good place to start to look?

Could be as simple as a gas cap. Evaporate is vacuum pressure to the gas tank . A rusty fill nozzle possibly?

I heard gas tank needs dropped to replace ???? You should never listen to what you heard from someone who has no clue ! P0442 is a small leak DTC P0442 Evaporative Emission (EVAP) System Small Leak Detected. You really should take it to a qualified repair shop .

EVAP Leaks P0442 and P0455

The evaporative emission system is tested by applying vacuum to the EVAP system and monitoring for a vacuum decay. The PCM monitors the vacuum level through the fuel tank pressure sensor signal. At an appropriate time, the EVAP canister purge solenoid valve and the EVAP vent solenoid are turned on, allowing the engine to draw a small vacuum on the entire evaporative emission system. Once the desired vacuum level has been achieved, the EVAP canister purge solenoid valve turns off, sealing the system. A small leak in the system will cause DTC P0442 to set.

Wells EVAP Training with Sgt Tech P0440 P0441 P0442 etc

Check the purge solenoid under the hood common problem in mazda 5 6 cx7.

The purge solenoid is by the engine and is connected to the vacuum system. Check the vacuum lines going to this and the lines that may be connected to the vacuum port it comes from. Check for seals on the solenoid if it is directly in the intake manifold. Other things to check are the lines (plastic) that go to the charcoal canister and fuel tank. If the light has been on for a while I would start with the pugre solenoid. If you have a vacuum leak there it would go from small to gross.
Small leaks are checked by the ECM constantly, gross leaks are some that has broke/cracked.

P0440 code is an Evaporative Emission System. That means you have a vacuum leak, start with the gas cap check that it is on prop. Check under the hood for a bad vacuum hose. The Dakota has a small hose that runs to the map sensor that will rot and leak. Hope this helps.

Try checking The last two on the list.

P0440 Generic Definition

EVAP (Evaporative Emission System) small leak/no flow condition
- The Evaporative Emission system is monitored for it's ability to hold vacuum.

Probable Cause[s]

1. Defective or loose fuel cap
2. EVAP canister or hose cracked-not connected
3. Purge or vent solenoid defective
4. Vacuum leak at engine

OBD II Code P0442

• • il
  • Print
  • Twitter
  • Facebook

Evaporative System Malfunction, Small Leak Our emissions expert has put together the following information about the P0442 fault code. We have also included diagnostic procedures you can take to your repair shop if the mechanic is having difficulty analyzing the code.
Related Information Check Engine Light
Emission Gas Definitions

OBD II Fault Code

• OBD II P0442

Fault Code Definition

• Evaporative System Malfunction, Small Leak

Symptoms

• Check Engine Light will illuminate
  
• In most cases, there are no adverse conditions noticed by the driver
  
• In some cases, there may be a noticeable fuel odor caused by the release of fuel vapors

Common Problems That Trigger the P0442 Code

• Defective or damaged fuel cap
• Distorted or damaged Fuel Tank Filler Neck
• Small tear or puncture in the Evaporative system hose(s) and/or Carbon Canister
• Defective Fuel Tank Sending Unit gasket or seal
• Small split in a seam of the Carbon Canister
• Defective Evaporative Vent Valve and/or Evaporative Purge Valve
• Defective or damaged Fuel Tank
• Defective Fuel Tank Pressure Sensor
• Defective Leak Detection Pump
• Slightly loose and/or worn clamps or hardened O-rings anywhere in the EVAP system

Common Misdiagnoses

• Fuel cap
• Evaporative Purge Valve
• Evaporative Vent Valve

Basics
The evaporative control (EVAP) system captures any raw fuel evaporating from the fuel storage system (e.g. the fuel tank, filler neck, and fuel cap). Under precise operating conditions-dictated by engine temperature, speed, and load-the EVAP system stores and purges these captured fuel vapors back into the combustion process.
Want to Learn More?
The EVAP system is designed not only to capture, store, and purge any raw fuel vapors that leak from areas in the Fuel Storage system, but also to run a series of self-tests that confirm or deny the operational and vapor holding ability of the system. This is an important task because at least 20 percent of vehicle-produced air pollution originates from malfunctioning Vehicle Fuel Storage systems.
There are many ways to "leak test" the EVAP system, but most perform the leak test when the vehicle is sitting (like over night) or during the initial start-up after the vehicle has been sitting over night. The EVAP system's operational performance is also tracked by the Power Train Computer by reading the change in the oxygen sensor voltages and short term fuel trim whenever the stored vapors are released or "purged" back into the combustion process. These values should indicate that fuel is being added to the system and that the overall mixture is getting richer. The purging process occurs when the vehicle is under acceleration, which is when most vehicles require additional fuel.

P0442 Diagnostic Theory for Shops and Technicians
The P0442 code indicates that there is a small leak in the EVAP system, but this is somewhat misleading. What the code really indicates is that the EVAP system will not hold a specified level of vacuum for a specified amount of time when it performs its leak test.
Here is how the evaporative leak test is performed by the Power Train Computer:

1. When the leak test is performed, the vehicle must have been sitting for at least four to eight hours so that the engine temperature and outside air temperature are identical. There must also be between 15 and 85 percent fuel in the tank-this is to provide a baseline for the test since gasoline and diesel are volatile fluids that expand and vaporize easily with warm temperatures.
2. When the leak test initiates, the Vapor Canister Vent Valve is closed to prevent any fresh air from entering the EVAP system. The Purge Valve is also sealed off.
3. The Leak Detection Pump operates to build a vacuum in the entire Evaporative System (see the Leak Detection Pump information below). After a specified time interval-usually about ten seconds-the Purge Valve is shut off and the vacuum level in the system is measured by the Fuel Tank Pressure Sensor.
4. Finally, a countdown initiates, which measures the rate at which the vacuum decays in the system. If the vacuum decays faster than the specified rate on two successive tests, then the Power Train Computer will fail the EVAP system and trigger the P0442 code. Most modern EVAP systems will fail the leak test with a pin-sized hole anywhere in the EVAP system, which amounts to 0.020 of an inch or a ½ millimeter.

Which code specifically? Do not assume you need a new solenoid. Our recommendation will depend on the specific code and some troubleshooting results. I usually recommend checking over all the EVAP vacuum lines and the gas cap too whenever there is a purge valve code. Check the vacuum lines at the cannister in the left rear bumper. I will paste info on the purge solenoid below.

P0440 Evaporative emission (EVAP) system - malfunction

Possible causes: Hose connection(s), intake leak, EVAP canister purge valve

P0441 Evaporative emission (EVAP) system - incorrect flow detected

Possible causes: Hose connection(s), intake leak, EVAP canister purge valve

P0442 Evaporative emission (EVAP) system - small leak detected

Possible causes: Hose connection(s), intake leak, EVAP canister, EVAP canister purge valve

P0443 Evaporative emission (EVAP) canister purge valve - circuit malfunction

Possible causes: Wiring, EVAP canister purge valve, ECM

P0444 Evaporative emission (EVAP) canister purge valve -open circuit

Possible causes: Wiring open circuit, EVAP canister purge valve, ECM

P0445 Evaporative emission (EVAP) canister purge valve -short circuit

Possible causes: Wiring short circuit, EVAP canister purge valve, ECM

P0450 Evaporative emission (EVAP) pressure sensor - circuit malfunction

Possible causes: Wiring, EVAP pressure sensor, ECM

P0455 Evaporative emission (EVAP) system - large leak detected

Possible causes: Hose connection(s), intake leak, EVAP canister, EVAP canister purge valve

P0456 Evaporative emission system - very small leak detected

Possible causes: Mechanical fault, hose connection(s), EVAP pressure "sensor

P0457 Evaporative emission system - leak detected (fuel cap loose/off)

Possible causes: Mechanical fault, hose connection(s), EVAP pressure sensor

P0458 Evaporative emission system, purge control valve -circuit low

Possible causes: Wiring short to earth, EVAP valve

P0459 Evaporative emission system, purge control valve -circuit high
Possible causes: Wiring short to positive, EVAP valve

Evaporative Emission Purge Solenoid

Description & Operation
The duty cycle EVAP canister purge solenoid (DCP) regulates the rate of vapor flow from the EVAP canister to the intake manifold. The Powertrain Control Module (PCM) operates the solenoid.
During the cold start warm-up period and the hot start time delay, the PCM does not energize the solenoid. When de-energized, no vapors are purged. The PCM de-energizes the solenoid during open loop operation.
The engine enters closed loop operation after it reaches a specified temperature and the time delay ends. During closed loop operation, the PCM cycles (energizes and de-energizes) the solenoid 5 or 10 times per second, depending upon operating conditions. The PCM varies the vapor flow rate by changing solenoid pulse width. Pulse width is the amount of time that the solenoid is energized. The PCM adjusts solenoid pulse width based on engine operating condition.
Removal & Installation
The duty cycle evaporative (EVAP) canister purge solenoid is located in the engine compartment near the brake master cylinder.

1. Disconnect electrical connector at solenoid.
2. Disconnect vacuum lines at solenoid.
3. Lift solenoid slot from mounting bracket for Removal & Installation.

To Install:

1. Position solenoid slot to mounting bracket.
2. Connect vacuum lines to solenoid. Be sure vacuum lines are firmly connected and not leaking or damaged. If leaking, a Diagnostic Trouble Code (DTC) may be set with certain emission packages.
3. Connect electrical connector to solenoid.
   

Purge solenoid location:


EVAP cannister location:

PO442 is the data trouble code for (evaporative emission control system leak detected "small leak") it means that the OBD-II system has detected a small vacuum leak in the evaporative control system.

You will need to find the vacuum leak in the evaporative control system, check for cracked or broken vacuum lines and hoses, especially the vacuum hoses and lines around the evaporative (Evap) canister and the (Evap) solenoid. Also check the gas cap seal for damage.

Vacuum hoses and lines should be checked very well for any cracks or breaks, because they usually hide under the vacuum line or hose.

Hello shoretex...Yes sir you can repair this yourself...
p0442 is medium leak detected ...p0456 is small leak....and p0440 is a general evap system failure.. evap codes are a common thing. gas caps are an inexpensive place to start. There are two types of evap hoses on the Dodge... hard plastic and soft rubber.... before you replace parts check the soft rubber first at the evap cans and pump located about a foot in front of the gas tank fill pipe on trucks located next to the transfer case or right behind the trans on the driver side. hard plastic lines will brake or rub through...check spots where lines come in contact with anything. this is a common thing with older trucks...hair line cracks will kick a p0442 code, and a p0445 code...When you find a leak, repair it, and rescan...sometimes there are several leaks, continue with inspection and repairs until you get it all fixed up.... Remember..start at simple and work from there...
i will post the evap. system in more detail to help you troubleshoot the problem.
EVAP System: The Evaporative Emission (EVAP) Control system used on all vehicles is the charcoal canister storage method. This method transfers fuel vapor from the fuel tank to an activated carbon (charcoal) storage device (canister) to hold the vapors when the vehicle is not operating. When the engine is operating, the fuel vapor is purged from the carbon element by intake air flow and consumed in the normal combustion process. The evaporative system includes the following components: *Fuel tank *Evaporative emission canister vent solenoid *Fuel tank pressure sensor *Fuel pipes and hoses *Vapor lines *Fuel cap *Evaporative emission canister *Purge lines *Purge valve solenoid EVAP System Operation: The EVAP purge solenoid valve allows manifold vacuum to purge the canister. The Powertrain Control Module (PCM) supplies a ground to energize the EVAP purge solenoid valve (purge on). The EVAP purge solenoid control is Pulse Width Modulated (PWM) or turned on and off several times a second. The EVAP canister purge PWM duty cycle varies according to the operating conditions determined by the mass air flow, the fuel trim, the engine coolant temperature, and the intake air temperature. For certain EVAP tests, the diagnostic will be disabled if the TP angle increases to above 75% . The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring for vacuum decay. The fuel level sensor input to the PCM is used to determine if the fuel level in the tank is correct to run the EVAP diagnostic tests. To ensure sufficient volume in the tank to begin the various diagnostic tests, the fuel level must be between 15% and 85% . The PCM monitors the fuel tank pressure/vacuum level via the fuel tank pressure sensor input. Results of Incorrect Operation: Poor idle, stalling and poor driveability can be caused by the following: *Malfunctioning purge solenoid. *Damaged canister. *Hoses/lines split, cracked and/or not connected properly. Evidence of fuel loss or fuel vapor odor can be caused by the following: *Liquid fuel leaking from the fuel lines *Cracked or damaged canister *Inoperative canister control valve Vacuum hoses that are: *Disconnected *Mis-routed *Kinked *Deteriorated *Damaged The evaporative leak detection diagnostic strategy is based on applying vacuum to the EVAP system and monitoring vacuum decay. The PCM monitors vacuum level via the fuel tank pressure sensor input. At an appropriate time, the EVAP purge solenoid and the EVAP vent solenoid are turned on, allowing engine vacuum to draw a small vacuum on the entire evaporative emission system. After the desired vacuum level has been achieved, the EVAP purge solenoid is turned off, sealing the system. A leak is detected by monitoring for a decrease in vacuum level over a given time period, all other variables remaining constant. A small leak in the system causes DTC P0442 to be set. If the desired vacuum level cannot be achieved in the test described above, a large leak or a faulty EVAP purge solenoid is indicated. This can be caused by the following conditions: *Disconnected or faulty fuel tank pressure sensor. *Missing or faulty fuel cap. *Disconnected, damaged, pinched, or blocked EVAP purge line. *Disconnected or damaged EVAP vent hose. *Disconnected, damaged, pinched, or blocked fuel tank vapor line. *Disconnected or faulty EVAP canister solenoid. *Disconnected or faulty EVAP vent solenoid. *Open ignition feed circuit to the EVAP vent or purge solenoid. *Damaged EVAP canister. Any of the above conditions sets DTC P0440. A restricted or blocked EVAP canister vent path is detected by drawing vacuum into the EVAP system. The PCM turns off the EVAP vent solenoid and the EVAP purge solenoid (EVAP vent solenoid Open, EVAP purge PWM 0% ). The PCM monitors the fuel tank pressure sensor input. With the EVAP vent solenoid open, any vacuum in the system should decrease quickly unless the vent is blocked. A blockage is caused by the following conditions: *Faulty EVAP vent solenoid (stuck closed). *Plugged, kinked, or pinched vent hose. *Shorted EVAP vent solenoid driver circuit. *Plugged evaporative canister.

Good luck shoretex, hope this helps...please take time to rate me a fixya.