Anybody know what code PO171H PO174 H ,Trim System Lean Bank 1 & Trim System Lean Bank 2, means?

 

Hi Pio,

Those codes are commonly set if the motor has an aftermarket air intake. They occur with most brands intermittently, generally when decelerating under very light or no throttle.

Recommend clearing the codes. Go for a ride. Hammer the car. and recheck the codes. They'll almost assuredly not reset.

If they do, check all your airpath connections for tightness of fit.

Ranger

 

First off, when ever Ranger speaks, you stand and listen!!!!!
Ranger....... There is a thread on a local forum in Colorado about your 10.85!!! First AWESOME!!! now come to Colorado and teach me that!!! Second you should read it, too bad there are sooo many haters (of course, cause they love them rustangs!)


Back on Topic. Definatly try all what Ranger said over and over and once you are sure that isn't it, do this: I have had my 03Z for almost 3 months now and for the first month and a 1/2 I had the same problem. I have a Blackwing CAI (this is how it was when I got it). Upon delivery of my Z the SES light was lit. Long story short after talking to the likes of Halltech and other people familiar with this happening after a CAI install this was the conclusion. In 02-04Z's the MAF's do not have a screen (that's the only 3 years, even the new ones do now). Some AIR is getting by the sensors unmetered (due to the higher amount of air going through now). Causing the o2's to see leaning air then it was expecting, so it corrects and this keeps on going on till it gets to a point (+24%?) then it throws the codes, cause it can't adjust anymore. During my month and a 1/2 of trying to fix this, we (local Chevy delearship) cleaned the original MAF, Replaced it with an OEM, finally replaced it with a newer Z screened MAF..... bottom line, the SCREENED MAF fixed my problem (hasn't come back in the last month and 1/2)! A lot of people fixed this by getting a tune, I would rather know that the MAF is metering everything correctly then covering up something.

 

Fly-in coaching is a specialty of mine. Not inexpensive though.

As for those pesky codes.

I ran an 02 Z06 with a Halltech Tric for three years and most of 30K miles. The lean codes occurred occasionally. The circumstances were never under load; were it then, I'd have a concern. Rather it was always off-throttle descending a hill. So I never worried about them because they were transitory and always showed as history codes, not current ones.

So I kept my MAF stock and the car ran well for me and for its two subsequent owners.

Ranger

 

ahhhhhhh. OK, I am broke, so I will just have to wait to you come around my way!!! Or if I make it back to where my family lives now, just west of DC in VA.

I was fortunate that they had NO CHOICE but to fix it, since I got it that way (and colorado law says you have to be able to pass emissions upon purchase of a vehicle). If I would have added the CAI and went with it and tried to get it fixed under warrenty for example, they would have just blamed the CAI, and said go back to stock. I myself never had any performance issues with the SES light on either, but wanted it perfect! Them getting a new MAF (with a screen) was A LOT cheaper then putting the air system back to stock.

 

After I put a Blackwing on my 02' Z06, I started getting the same codes intermittently, just did what Ranger said and reset the codes. I made sure everything was tight after the installation making sure there were no air leaks. No problems, just reset it after it happens since everything else looks good.

 

Guys, thanks for the help. I will check the intake from top to bottom and reset the codes. I keep re-setting and it keeps popping back up. The idle has been erratic lately, the only change is that I dropped in 3.90 gears, but that shouldn't screw with that code, right?

 

Gears should have no impact on idle quality.

Rough idle can occur if there is a airpath leak. Rechecking all the clamps for proper seating may fit it.

Ranger

 

Well, this is what the forum is all about!!! The MAF housing had come lose from the Halltech filter. I tightened everything up and cleaned out the clutch fluid while I was at it, reset the codes and BAM!!! its perfect.

Ranger and all, thanks a bunch