Trouble with Lean codes and cat codes :(
 

hi all,
I've had my jag (2003 2.5) for about two years now and other than having to replace a coil pack I've been problem free, transfer case and rear end were full and clean like new at my present 116k mileage. tranny shifts well.

although after 6 months of owning the car the car started throwing a code for a 02 sensor I wish I remembered which one maybe its the cause of my issues.. but now the codes that are present and refuse to go away no matter what i do are;

po171b b1 sys too lean
po174b b2 sys too lean
po430 cat sys efficency below threshold

some time ago I found the circular solenoids/sensors on the intake to be leaking sucking air so i sealed them and rest the code but after the sucking noise was gone the codes were still present.

I've also looked into this on this forum and tryed following the lean condition breakdown;

"The most common issues for lean codes are:

1. Vacuum leaks - check for failed or loose vacuum lines, leaking intake gaskets, intake air tubes loose or any other source of un-metered air leaks (leaks after the Mass Air Flow Sensor)
2. Restricted fuel filter or bent/pinched fuel system lines
3. Incorrect input from other sensors, such as the Mass Air Flow Sensor, which may not always drop a separate code
4. Engine misfire � Yes I know this one may seem weird. You might think that if there is a misfire then you will have all that unburned fuel and it should read rich; right? Well the O2 sensors read only oxygen content in the exhaust, so if you have all that unburned fuel from incomplete combustion then, you guessed it, you also have all that unburned oxygen. High O2 content in exhaust equals a lean reading! There are also some other possibilities such as an internally leaking EGR system, (but this will typically set a separate code). A leak in the exhaust system before the O2 sensor will also cause incorrect readings. And always check for after- market modifications. These can throw a wrench into the works! The only other possibilities (however unlikely), are wiring issues, computer concerns or a bad O2 sensor!"

This check engine lamp is slowly driving me to the funny farm so besides unpluging it or totaling my car and anyone offer me sound advise? (I'm a diesel mechanic and work of gas engines for a hobby so I am versed)

thankyou all:icon_shrug:

I had two codes saying I think the same with two banks being lean and I replaced two rubber gaskets that are on the two black air control motors on the upper intake they were bad causing a a air leak

Lean codes sound like maybe an 02 sensor? But first check for vaccuum leaks. Brake booster area and upper left block.

didnt notice it last time i checked but looking at it today the pcv rubber hose had a 2 inch crack down the middle! hope now that its replaced fixes the issues!

Beat me to the post! That original PCV hose is a joke... You'll notice the new one is a far better design. That should take care of your lean codes but keep an eye on that cat code. There is a good possibility its bad due to the PCV leak in the first place. Good news is that its P0430 and not P0420. The bad cat is the one in front that is more easily accesible. P0420 is the rear which requires a LOT of work to get it out.

Lean codes are gone but looks like i need a front cat.
Dealer wants big money they quoted me fir the parts.

C2s21143 cat 606$
c2s2695 gasket 11.59
c2s51801 o2 112.53
c2s38497 o2 114.16

does anyone know of a place to save money?

I just started doing some research for parts depending on what codes I get back next Monday. I found Bosch o2 sensors for $59 (free shipping) Amazon.com: Bosch 15627 Oxygen Sensor, OE Type Fitment: Automotive

and the front cat on eBay goes for around $250. If you have a mechanic that will do the labor with your parts you can save big money, which is what I am planning to do.

Follow MarcVIII's thread on the front cat. He used a benchmark 49 state legal cat (about $250) and is still having problems with the MIL. I know Davico makes what is supposed to be a better one for the rear but I can't seem to find one for the front.