Question about Chevrolet Cars & Trucks
Code 300 is for a random miss which may be tough to track down.
Code 442 is for a small leak detected in the EVAP system and 446 is for a problem with the performance of that system. The EVAP system vents fumes from the gas tank to the vapor canister. Sometimes the small leak is the gas cap not being on tight, and sometimes it is a component or hose in the system.
Posted on Feb 07, 2014
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Posted on Jan 02, 2017
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.
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Posted on Jul 20, 2009
SOURCE: 2001 chevy impala code p0446
This is an indication of a fault with fuel evaporative control system. The system consists of vapour coming off from 'sealed' (always check that your gas cap is on good and tight after refills) fuel in the tank being trapped in a carbon filled canister or trap. Also fitted to this trap is a vent tube with a solenoid operated valve to the atmosphere and a purge tube with a solenoid operated valve to the inlet manifold. When the engine cold the purge valve remains closed. Once warmed up the purge valve opens to allow fuel vapour to contribute to the intake to the engine. When the engine revs higher the vent valve opens to allow external air to help flush out vapour from the trap to the engine. The error code says that there is an error with this vent valve (most likely that it is not opening when it should). To check put a voltmeter across the electrical contacts on it and just check for resistance /continuity. If there is no continuity the solenoid has most likely burnt out. A further check is to apply 12volts across the electrical contacts and this should be seen to open and close the valve. If you find that this fault is any way affecting the function of the car, as a temporary measure simply block the purge tube as it enters the inlet manifold (sometimes on the throttle body). This is only a temporary fix as if left like this it will fail its next test.
Posted on Jun 23, 2010
From www.hondasuv.com: The P1399 random misfire along with one or more of these codes: P0301, P0302, P0303, P0304 -- indicates a problem with the valves. The B20 engines in the 1997-2001 CR-Vs are known to have problems with valves tightening and then 'burning'.
So the first question is when was the last time you adjusted the valves? If you don't know or never have, then have them adjusted. Soon...
The P1399 random misfire along with one or more of these codes: P0301, P0302, P0303, P0304 -- indicates a problem with the valves. The B20 engines in the 1997-2001 CR-Vs are known to have problems with valves tightening and then 'burning'.
Posted on Jan 04, 2011
Tips for a great answer:
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Oct 26, 2012 | Cars & Trucks
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.
Remove and reinstall the gas cap, clear the codes, and drive for a day and see if the codes come back.
Otherwise, replace the gas cap, or
Inspect the EVAP system for cuts/holes in tubes/hoses.
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