Persistent P0171 and P0174 codes
 

Hey All,

I have a 2008 LR2 3.2L with a hair over 90k miles. I have two codes keeping me from passing state emissions - P0171 and P0174. Those codes are persistent, and appear within 10 miles of being reset. I also get random P0172 and P0175 codes. Not sure how I am getting both lean and rich codes, but it is.

My Fuel Trims seem to only be lean at idle, and even out to at least acceptable ranges above 1500RPM. So I would assume vacuum leak. Dealership has not been able to find one. Thus far I have replaced the MAF sensor, Air Filter, FRP Sensor. The dealer replaced "Vacuum diaphragm"? and the PCV Oil Trap. I left the battery off overnight after the dealer repairs to reset LTFT's, but codes were back within 20 miles.

I am still leaning towards a vacuum leak due to the trims, but have not been able to find one either visually, smoke tested, or carb cleaner tested. I have it scheduled to be back to the dealer on Monday, but was wondering if anyone else has had this persistent CEL issue? I have already paid about $700 to Land Rover of Salt Lake, and my LTFT's are still pegged at 24 at idle.

Thanks in advance!

Disconnecting the battery will not clear the codes. You need to use an OBD2 scanner with a clear codes function.

I got the same codes on my 2008 LR2 and the problem was a dirty MAF. I cleaned it with some spray and the codes did not return. When I talked to the dealer about it, they told me they don't clean the MAF, they only replace it. Another reason to try less expensive DIY solutions before going to the dealer.

Thanks for the reply, and the heads up on the codes. I replaced the MAF sensor with an OEM I got at British Parts of Utah. Much cheaper than the dealer. Unfortunately, it didn't resolve the issue. I am going to stick her on a lift at a friends tonight and check for leaks in the exhaust system, and probably clean the TB. I'll update on if the codes stick around or not.

Have you checked fuel pressure? Perhaps you have a weak/dying pump?

Take a look at this thread

Your problem might be the PCV valve

2008 XC90 3.2L with codes P0171 and P0174 - Help - FWD/AWD 1999 - 2010 - Volvospeed Forums

I've been thinking about replacing mine but I haven't yet (I am getting a little oil vapor near the diaphram but no code yet)

Here is where I was going to buy it

PCV for LR2 LR023777 (comes with the gasket)


https://www.potamkinparts.com/oem-pa...MtMmwtbDYtZ2Fz $119 + shipping


Happy Motoring

Paul