4.2 ltr 6. What are the probable causes of DTCs P0170 and P0496?

SOURCE: Check Engine light

that code definition is "Evap high purge flow fault". It means you may have a problem with the evaporative system. this system routes fuel fumes back to the fuel tank. If you want to try and clear this code, find the radio code for your car and then disconnect the battery for 30 seconds. Reconnect the battery and the check engine light should be out. You will then need the radio code to reset your car stereo. the check engine light may stay off if the condition was a transient one. If not, the light will come back on after you drive the car two drive cycles. That is: two starts, warm ups and shut downs. If the light returns, have a mechanic check it out.

Harvey N Tawatao

• 3854 Answers
• Posted on May 02, 2009

SOURCE: CHECK ENGINE LIGHT ON CODE P0170

DTC P0170 applies to fuel trim malfunction on all 2.4L vehicles, 3.0L Federal vehicles and right bank (bank 1) on 3.0L California vehicles. 
DTC P0173 applies to fuel trim malfunction on left bank (bank 2) on 3.0L California vehicles.
DTC Set Criteria (2.4L)
Engine is in closed loop control. Intake air temperature is more than 14°F (-10°C). Barometric pressure is more than 11 psi (76 kPa). Volume Airflow (VAF) sensor output frequency is 88 Hz or more. Code will set if long-range fuel correction is less than -12.5 percent, or more than +12.5 percent, for 5 seconds and short-range fuel correction is less than -10 percent, or more than +10 percent, for 5 seconds. 

Engine is in closed loop control. Intake air temperature is more than 14°F (-10°C). Barometric pressure is more than 11 psi (76 kPa). VAF sensor output frequency is less than 88 Hz. Code will set if long-range fuel correction is less than -12.5 percent, or more than +12.5 percent, for 5 seconds. On 2.4L code will also set if short-range fuel correction is less than -15 percent, or more than +15 percent, for 5 seconds. On 3.0L Federal code will also set if short-range fuel correction is less than -13.5 percent, or more than +13.5 percent, for 5 seconds. 

Have the O2 Sensor changed on the Right Bank, ( passenger side of the Engine, or where the # 1 cylinder is.)
Good luck and hope this helps

SOURCE: 2001 C320 with 50,000 miles failed Pa Emissions

The codes are for the Mass Air Flow Sensor. It is located between the throttle body and the air filter case. You will see it has a plug in the side. Unplug and remove it by taking the hose clamps off each end. Once you have it out, clean it out with a good throttle body/intake cleaner. Allow it to dry and reinstall. If the light continues to come on, you will need to replace it. Cleaning has worked for some.

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SOURCE: I have 1997 F150,check engine light came on, took

maybe a fuse is blown? did you have the mechanic check the fuses? or even check all your relays and wiring?

SOURCE: 1994 GMC Jimmy engine runs rough when cold; smooths out when warm

you need to have the codes checked to know what direction to start repairs,Autozone does this for free