Outlaw55

good afternoon everyone, boy do I have a tough issue going on with my truck. so I have a 2003 f150 4.6 xlt 4x4. love my truck but when it breaks, it breaks bad. a couple months ago i was replacing the oil pan gasket and discovered broken pieces of my timing chain tensioner in the pain..... long story short i had to replace all my timing components, which was a difficult, but and extremely good learning opportunity. while we were putting everything back together we discovered the egr tube, (tube from exhaust manifold to egr) was pretty loose around the nut fitting. more than likely it was just rusted away on the inside. so anyways after we put it all together and drove around sure enough, p0405 came up. the first thing i did was try and rap the egr tube in some of that exhuast rap stuff you can get at the parts store. i reset the code and it came back on about 2 days later. so at this point i started thinking maybe we had damaged the DPFE sensor while putting it back on. i ran some troubleshooting after whatchin ScannerDanner on youtube and did exactly what he said. I grounded the EVR to actuate the egr valve open and sure enough the DPFE sensor had to low of a reference voltage. thus giving me the p0405 code ( Exhaust Gas Recirculation Sensor 'A' Circuit Low). well i went and replaced that $75 sensor and guess what.... code came back again. so now im stuck and not sure where to proceed to next. my truck runs perfect and acts as if there is no issue. just having the check engine light on is bothering me. so im reaching out to anyone who may be able to help or give some advice. I am not a ford tech. but i am certainly not incompetent either. Im a diesel tech. for the USAF, and unfortunately ford's are not something we specialize in ha ha. all comments/help welcomed, thank you!

Fordrocks689

From what I read, I would either try finding a used egr and see if that's the issue (unlikely since it's running good) or swap out the exhaust egr pipe since it's failing and you wrapped it. Even tho it's wrapped it sounds like it didn't fix the problem.

Outlaw55

yeah thats what i was thinking unfortunately. im afraid of f'n up the manifold when taking that pipe off..

akdoggie

Since it is a 405 code, that usually means a bad wire or carbon build up in the EGR valve itself. Your line problem could cause a leak, but that should throw a different code.

I think I'd pull the EGR and clean it. While you have it off, check it to see if it moves freely. I'd lean to the valve first. You can have a bad valve, and it still run decent, but it will set CEL's all day long.

white89gt

You also should check both hoses for the DPFE for leaks, cracks, etc. Your DPFE may also be causing the code. I've seen a DPFE throw a P0405 because it had shorted out.

akdoggie

What he said also ^^^^^

Usually that is a 401 or 1401 code, but 405 does get set sometimes from the sensor reading being too low. Good catch Whitey.

Outlaw55

i agree thats why i trouble shot and replaced the dpfe sensor already. the code is still there

Outlaw55

ill have to check out the EGR valve itself for sure. i may need to smoke test and see if i have anymore leaks