marine02xx

Folks,
This post is for those who are fighting the “P0402” code. I noticed my 2001 F-150 (4.6) would periodically hesitate, accelerate slowly and noticed a decrease in miles per gallon. Instead of wasting money on unneeded parts (like some people do), I tested the DPFE sensor, the EGR solenoid, the EGR valve and the vacuum lines associated with the EGR system. They were all good. However, I was still receiving the P0402 code after cleaning and testing the aforementioned parts. I figured if I still have an insufficient EGR flow, it probably means there is a blockage within the EGR system internal. So I decided to inspect the throttle body and FOUND THE PROBLEM! The chambers in the throttle body that lead to the EGR valve was clogged with carbon! Take a look…

In order to remove the throttle body, I had to remove the plastic air induction parts, remove the ERG valve from the throttle body, and disconnect all the electronic connectors, hoses on the throttle body and accelerators cables. The throttle body is held down by four bolts. I removed the four bolts and the throttle body. I noticed two small ports that lead to the EGR valve chamber were clogged with carbon. I removed all of the parts connected to the throttle body and removed as much carbon and dirt from this section as possible.

After thoroughly cleaning the throttle body, I cleaned the other parts that were connected to the throttle body, reassemble them, and mounted the throttle body to the intake. I noticed a significant improvement in the engine’s idle and acceleration. So, before you waste money buying EGR parts to solve the P0402 problem, please test the parts to see if they actually work. If they are functioning properly, clean the throttle body assembly. This should solve your insufficient EGR flow problem.

BadF-150

i may have to do this because i have the same code along with running lean on both banks...

2000fordf1504x4

I wounder how long it will be before I have to do this to mine

83fordboy

I'm wondering if my '97 has the same set up. I have been getting that code for a while and just recently it has started running really rough. I'm guna tear into it tomorrow and hopefully figure it out.

marine02xx

Also, if you don’t have a solvent tank, buy at least three cans of carb / throttle body cleaner (approx. $2.50 – $3.00 a can). I also recommend buying a gun cleaning kit from Wal-Mart or a gun store. You can use the chamber and bore brushes to clean out carbon in hard to reach areas. I scraped the chambers with a screw driver, but came to that revelation after I was finished. You also want to clean the intake as much as possible while you have the throttle body off.

2000fordf1504x4

K thanks