99 explorer check engine light

SOURCE: The check engine light stays on or comes back on

the problem you have is related to your EVAP valve, have it checked cause it can be a lot of things and might be necesary to replace.
hope this helps

SOURCE: 01 Ford Expedition. Check Engine light and failed Smog check.

whoever installed the egr valve, if it wasnt you, just cleared the engine codes, thus giving you this problem once again. Get it scanned at autozone, and go from there.

jolaw11

• 13 Answers
• Posted on Jun 28, 2009

SOURCE: 1981 ford bronco failed emissions twice

Look behind the motor, next to the firewall. There's a vacuum check valve that keeps the air gulp pump from pressurizing the crankcase. Mine was shot; had the same symtoms. Also, make sure that the EGR valve is closing at low idle.

You don't need an engine light to check the codes. First, do a KOEO (key on, engine off), but, let me tell you, when this happened to me (1986 Full size with 302 EFI, multiport injection) NOTHING showed up. No one, not Ford, not emission specialists, nada, knew the vacuum check valve existed.

By the way; are you getting motor oil in the air filter housing?

SOURCE: I have a 1997 Ford Explorer. Check engine light

Here is a list of possible causes, hope this helps.


Your vehicle’s computer system has self-testing capability. When the computer senses that there is a problem with one of the components or sensors it stores the correspondent trouble code(s) in its memory and lights up the "Check Engine" or "Service Engine Soon" light to tell you that there is a problem and you need to diagnosed and repaired it. The list of possible codes number in the hundreds. The code itself doesn't tell exactly what component is defective - it only indicates where to look, or what engine parameter is out of normal range. You or a technician will have to perform further testing to pinpoint cause and the proper repair. Even if you reset the light, if the underlying problem is not addressed it will come back on.

Possible Causes Setting Conditions

• Air leaks after the MAF sensor, or leaks in the PCV system
• Vehicle running out of fuel or engine oil dip stick not seated
• EGR valve gasket is damaged or leaking around the gasket
• Exhaust leaks before or near where the HO2S is mounted
• Fuel injector(s) not supplying enough fuel
• Fuel system not supplying enough fuel during high fuel demand conditions (e.g., the fuel pump may not supply enough fuel)
• MAF sensor is dirty (can cause PCM to underestimate airflow)
• Intake gasket leak

SOURCE: the check engine light

CODE PO443 IS EVAP CANISTER PURGE SOLENOID CIRCUIT MALFUNCTION.