Evaporative Emission System | Leak Detected


•A loose or improperly affixed gas cap
•A non-conforming gas cap (i.e. not factory/original brand)
•A small leak/hole in a fuel vapor hose/tube
•Other small leaks in the EVAP system
•Faulty vent o-ring seal

Normally there is no drivability issues, but your computer may be trying to compensate and that might make it run rough.

 The most common cause for the 442 on the code "X" (OHV) engine is the EVAP Canister Vent Solenoid/Valve (will not fully seal)! Trouble code P0442 is a code indicating a small leak (0.040").

If the PCM was not activating the CANV solenoid, the PCM would likely set a P0455 code instead, indicating a large leak. The PCM only activates the CANV solenoid during specific operating conditions when it wants to perform the Evaporative Emission (EVAP) system monitor leak test.

 This will only occur once per drive cycle provided that conditions are right to activate it To test; Access the Canister Vent (CANV) solenoid on the carbon canister. Ground the Violet/White (VT/WH) wire and check to verify that the solenoid is mechanically closed, by attempting to blow through it.

 Normally there are no driveability issues with EVAP related problems.
 (Yet if there is a vacuum leak due to a purge solenoid or vacuum hose there will be!)

Ford Explorer P0442 Code Symptoms

The P0442 code on a Ford Explorer will often be thrown after the engine has a hard time starting after refueling. I’ve personally had this problem happen to me. You’ll fill up the vehicle and it just won’t start. Then, it’ll either start on the second try or after cranking the engine for a while.
If you’re old enough to have driven a carbureted vehicle, the old stomp the gas and crank the engine method does actually help start the Explorer.
Other than the difficulty in starting, the P0442 doesn’t seem to cause any other problems (at least in the short-term). You may also smell gas when driving.

Ford Explorer P0442 Code Defined

P0442 is a general OBDII trouble code, which means it has the same meaning regardless of who manufactured the vehicle. The code technically stands for:

Evaporative Emission System | Leak Detected

The EVAP system captures all fuel vapor from the fuel tank and sends them to the engine’s intake in order to be ignited in the normal combustion process.
When the Ford Explorer’s computer detects that the EVAP system is not holding any pressure, it will throw the P0442 code.

Ford Explorer P0442 Causes

There are many things that can cause the P0442 trouble code on the Ford Explorer. The most common problem is far and away from the first one listed below.

• EVAP Canister Purge Valve– The most common culprit with the P0442 trouble code and the Ford Explorer is going to be the vapor canister purge valve. When it goes bad, it typically causes issues with the vehicle’s idle speed. This is especially true right after you fuel up. It’s really easy to replace. There are a few clips that you need to find and remove. There’s a great YouTube video on diagnosing the problem below, as well as how to replace the part. It’s fantastic. This is almost always the problem. They are really cheap on Amazon too. Always make sure to verify the fit for your vehicle. There’s a tool to check the fit right there.
• Fuel Vapor Hose– A leak in the fuel vapor hose that leads from the fuel tank to the intake will definitely throw P0442 in your Explorer.
• Gas Cap Bad– A bad fuel cap can cause the P0442 code to be thrown for sure. The Explorer will typically be warning you to tighten the fuel cap. This is a great place to start. It’s a simple thing to fix and only takes a few minutes to swap a gas cap.
• Loose Gas Cap– A loose gas cap will also trigger this trouble code. So if it’s the first time that you have experienced this issue, you may want to go ahead and tighten the cap and see if the code clears itself. Just be aware that it may take the engine several cycles to clear the code.
• Fuel Tank Pressure Sensor– If the fuel tank pressure sensor has gone bad, it can cause all sorts of problems, including the P0442 code.
•  
• =====
•  
•  
  

  P0442 FORD - Evaporative Emission System Leak Detected Small Leak

         

  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 the fuel filler cap
• EVAP canister or fuel tank leaks
• EVAP system hose leaking
• Fuel tank leaking
  What does this mean?

Tech notes

The P0442 code means that the control module has detected a small leak in the Evaporative Emission (EVAP). Loose fuel tank filler cap is the most common cause that triggers the P0442 code.


What does this mean?

When is the code detected?

Malfunction is detected when the EVAP control system has a leak, the EVAP control system does not operate properly.

Possible symptoms







Engine Light ON (or Service Engine Soon Warning Light)

Possible a noticeable fuel odor caused by the release of fuel vapors


P0442 Ford Description
The Engine Control Module (ECM) tests the Evaporative Emission (EVAP) system for the following conditions:- Large and small leaks
- Excess vacuum
- Purge flow during non-commanded conditions
- Fuel Level and Fuel Pressure sensor faults
- EVAP Purge and Vent Valve faults

The ECM monitors the Fuel Tank Pressure sensor in order to determine the level of vacuum/pressure in the EVAP system. The ECM commands both the EVAP Purge Solenoid and the EVAP Vent Valve ON when the conditions are met in order to apply an engine vacuum to the EVAP system. The ECM commands the EVAP Purge Solenoid OFF once the system has reached a predetermined level of vacuum. This test verifies if a vacuum can be achieved in the EVAP system. Failure to develop a vacuum may be caused by a large leak or a restriction.

What Does P0125 Code Mean?

OBD-II Code P0125 is defined as a Insufficient Coolant Temperature For Close Loop Fuel Control

What does this Mean?
In order for the Powertrain Control Module or PCM to effectively control the fuel and ignition systems while, at the same time, minimize the emissions output from a vehicle, the engine cooling system must reach a critical operating temperature.
This temperature is typically between 160-170 degrees F and must be reached within 15 minutes after a 'stone cold' start. If the weather is extremely cold, say 10 or more degrees below zero, the coolant temperature must rise at least 70+ degrees from the 'stone cold' starting temperature. A 'stone cold' start is achieved when the vehicle is started after sitting with its engine off for at least 8 consecutive hours.
 If the coolant temperature stays below the 160-170 degree range or wanders above and below  this level, the PCM can't rely on the exhaust oxygen feedback data it receives from the oxygen sensors in the exhaust system. When this occurs, the PCM must rely on a crude 'limp home' type of fuel and ignition control program. This raises the level of exhaust gas pollution to unacceptably high levels and will trigger the check engine light.

P0125 Symptoms

• Check Engine Light on
• Vehicle may not shift into the highest gear at freeway speed
• Decrease in fuel economy
• In unusual cases, there are no adverse conditions noticed by the driver

Common Problems That Trigger the P0125 Code

• Defective Engine Thermostat
• Defective Engine Coolant Temperature Sensor
• Defective Intake Air Temperature Sensor
• Defective Cooling System
• Low Engine Coolant
• Dirty Engine Coolant, causing incorrect Coolant Temperature Sensor readings
• Defective, always running Engine Cooling fan(s)

Common Misdiagnoses

• Engine Cooling Fan
• Internal Engine problem
• Oxygen Sensor problem
• Engine Coolant Temperature Sensor problem

Polluting Gases Expelled

• HCs (Hydrocarbons): Unburned droplets of raw fuel that smell, affect breathing, and contribute to smog
• CO (Carbon Monoxide): Partially burned fuel that is an odorless and deadly poisonous gas

P0125 Diagnostic Theory for Shops and Technicians

Here's how to diagnose the P0125 code:

• It is critically important to record the freeze frame data to determine which operational mode set the code. Pay close attention to the MPH, TPS, LOAD, RPM, and of course, the Engine Coolant Temperature and Intake Air Temperature. These values will help determine if the vehicle was being driven at freeway or slower, in town driving speeds.
• Connect the scanner and select the most factory like data stream for the engine sensors. Start the vehicle (make sure the heater is off) and watch the Coolant Temperature values change.
• If the Coolant Temperature readings will not go above the 160–170º F mark within fifteen minutes, the thermostat is the most likely culprit.
• Be sure to verify that the engine coolant temperature readings agree with physical reality, so use a laser pyrometer to measure the temperature of the engine, so you don't mistakenly blame the engine cooling system for a problem that is being caused by high resistance in the coolant temperature sensor, its connections or circuitry.

When doing the P0125 diagnosis, be sure to verify that either the electric or mechanical cooling fan is not stuck on because this will cause the engine to run at a very reduced operating temperature. Also, be sure to verify that the Intake Air Temperature Sensor readings are within reason, meaning that they are not too hot or too cold in relation to the outside air temperature and under-hood air temperature.

A good rule of thumb is that the Intake Air Temperature reading is usually about 100º F below the Coolant Temperature readings after warm up. When cold starting the vehicle, the readings should begin at nearly identical values.