Suggestions to diagnose codes p0172 and p0175
Thread Starter
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Senior Member
Joined: Apr 2016
Posts: 315
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From: Central Wisconsin
Suggestions to diagnose codes p0172 and p0175
Hi All
2003 F150 5.4L XLT FX4 4R70W 4x4
So the other morning my CEL came on after a brief stop on my way to work. Using a simple scan tool (no live data) I discovered that I had p0172 and p0175 codes. I read that they indicate a rich condition on both banks. I also found that using a live data scanner (I do have access to one) I can narrow down what may be causing my fault. Anybody have experiance with this issue? Trouble shooting tips?
I was pointed toward the MAF as a possible culprit, anyone cleaned one before with positive results, what product did you use? I was also told occasionally the flex tube connecting the air filter to the intake can develop a hole causing this issue?
TIA for any advice
2003 F150 5.4L XLT FX4 4R70W 4x4
So the other morning my CEL came on after a brief stop on my way to work. Using a simple scan tool (no live data) I discovered that I had p0172 and p0175 codes. I read that they indicate a rich condition on both banks. I also found that using a live data scanner (I do have access to one) I can narrow down what may be causing my fault. Anybody have experiance with this issue? Trouble shooting tips?
I was pointed toward the MAF as a possible culprit, anyone cleaned one before with positive results, what product did you use? I was also told occasionally the flex tube connecting the air filter to the intake can develop a hole causing this issue?
TIA for any advice
Senior Member
Joined: Jul 2004
Posts: 6,200
Likes: 39
From: Easton, Pa.
The codes are for a detected rich condition by the Ox Sensors.
Check for the fuel regulator for leaking fuel back through the vacuum line into the intake.
Other causes are leaking fuel injectors, too high a fuel pressure, thermostat stuck open causing the cylinder head temperature sensor to richen up the fuel.
.
Leave the mass air meter alone and no, a hole in the intake tube will cause excess air and set Lean codes, not rich codes.
Good luck.
Check for the fuel regulator for leaking fuel back through the vacuum line into the intake.
Other causes are leaking fuel injectors, too high a fuel pressure, thermostat stuck open causing the cylinder head temperature sensor to richen up the fuel.
.
Leave the mass air meter alone and no, a hole in the intake tube will cause excess air and set Lean codes, not rich codes.
Good luck.
Thread Starter
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Senior Member
Joined: Apr 2016
Posts: 315
Likes: 0
From: Central Wisconsin
So check this out fellas...
I hadn't checked under the hood since the truck threw the rich condition codes, it's been raining here. So tonight after work something was squealing (pretty sure an idler pulley is going) so I popped the hood to have a look.
The first thing that caught my eye was the air cleaner assembly, because the clamp that holds it together was popped open and the filter was partially out. I put it back together and continued looking for the squeal. The only parts that aren't new on the front of my engine are the idler pulleys, AC compressor and alternator. I'm pretty confident it's an idler pulley.
Back to the original problem, so a coworker had a scan tool in his car and we cleared the CEL on my lunch break so it was off when I fired up the truck. I drove around for a little more than an hour after I put the air cleaner back together. At this point still no CEL, I'll update tomorrow after I've gotten home from work.
I hadn't checked under the hood since the truck threw the rich condition codes, it's been raining here. So tonight after work something was squealing (pretty sure an idler pulley is going) so I popped the hood to have a look.
The first thing that caught my eye was the air cleaner assembly, because the clamp that holds it together was popped open and the filter was partially out. I put it back together and continued looking for the squeal. The only parts that aren't new on the front of my engine are the idler pulleys, AC compressor and alternator. I'm pretty confident it's an idler pulley.
Back to the original problem, so a coworker had a scan tool in his car and we cleared the CEL on my lunch break so it was off when I fired up the truck. I drove around for a little more than an hour after I put the air cleaner back together. At this point still no CEL, I'll update tomorrow after I've gotten home from work.
