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Old 10-13-2007, 05:42 PM   #1
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P0171 & P0174

A hose that is part of my K&N Typhoon air intake system came loose,no doubt causing he P0171 AND P0174 codes and my Service Engine Soon light to come on. I tightened it yet the Service Engine Soon light is still on.

I understand that perhaps my Mass Air FLow Sensor is dirty or the DPFE sensor needs replacing. Can someone in simple,easy to understand language please tell me how to locate and clean the Mass Air Flow Sensor and how to locate The DPFE sensor?

thanks in advance
Mike Long
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Old 10-15-2007, 06:44 AM   #2
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Re: P0171 & P0174

Tools: One can of “Electrical Contact Cleaner” (do NOT substitute brake cleaner or carburator cleaner), and a #20 “Tamper-proof TROX” bit and/or driver.

Follow these steps carefully:

-Locate the MAF assembly, it is attached to the upper air cleaner box on the driver’s side.
-Disconnect the electrical connector completely, and place it aside
-Using the “TORX” driver, remove the two (2) screws that retain the sensor element in the body
-CAREFULLY pull the sensor element STRAIGHT up and out of the body
-Carefully inspect the sensor to verify that there are two (2) “cross wires” running from one terminal to the other (about 1/2” long), if either are missing, damaged, bent, or broken, the MAF assembly MUST be replaced as a unit.
-Clean off any deposits, junk, or oil from the sensor terminals on the post using the “electrical contact cleaner”. Not the electrical connector area!
-Allow to dry completely
-Carefully insert sensor element into body and secure with screws you removed earlier
-Re-attach the electrical connector
-Start the engine, and ensure everything operates normally, road test for performance.

I believe the DPFE is on the side of the throttle body and it has two vaccuum lines attached to it
You might want to test the EGR as well

To Test the EGR Valve:
Check all of the vacuum lines. Check the connections at 1. the valve, 2. the soleniod, and 3. the intake manifold.
Perform a vacuum leakage test by connecting a vacuum pump to the EGR Valve. Apply a vacuum of 5 to 6 in. Hg to the valve. The vacuum pump should hold the vacuum.
Remove the EGR valve and clean the inlet and outlet ports with a wire brush or scraper.

you should also try hooking up a multimeter to the wires. you need to turn the key on, but dont start the car. if you unhook the wires from the sensor, you should be able to put the meter probes into the snesor wires and get roughly 12volts.

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Old 10-15-2007, 11:17 PM   #3
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Re: P0171 & P0174

DPFE is a gray box that bolts to the rear-most bolt of the upperintake on 94-98.

It will have two vacuum lines, a green and red that come out of it. There are also two larger gray rubber hoses that connect down to the egr tube off the header.
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