[ihorjrt]

I have a bunch of problems with my 2003 Range Rover HSE. I tried everything and spent thousands on parts already and still can't figure out the problem. i just bought new O2 sensors and changed them couple months ago. i have the following codes:
PO171 - System too lean Bank 1
PO174 - System too lean Bank 2
PO135 - O2 heater circuit Bank 1 Sensor 1
PO141 - O2 heater circuit Bank 1 Sensor 2
PO160 - O2 circuit no activity detected Bank 2 Sensor 2
PO159 - O2 Circuit slow response Bank 2 Sensor 2
PO1172 - Ambient pressure sensor recognition value malfunction
If someone has any idea what I should try, or change please let me know. Any help will be appreciated, I am frustrated with this vehicle already.

 

[diff]

Welcome to the site. My wife is a Winnipeg transplant with family still there. We had the 171 which cleared after removing the sensor and replacing it and cleaning the connector contacts. Since it was only bank 1 i thought that the mac and other upstream stuff would not cause the code. When reassembled the fault cleared after several drive cycles. We also had significant bogging off idle during the cold weather-something that disappeared in the more recent warmer weather. So no real answer although crank position sensor, cam position sensor, plugged fuel filter have all been listed as causes-research the bimmer forums. We changed none of those things yet and she has returned to normal operations for the time being at least. Good luck with your search. I think there are temperature dependant issues but not sure what part is affected by the cold. I bought contact cleaner for the electrical connectors which is mentioned thruout this site as a useful thing to do. I only scraped the o2 sensor pins and used a touch of anti seize on the sensor threads but no proof that that solved the problem. let us know if you solve any of your issues

 

[Spinz]

There is probally a crack in the weld on the top side of the exhaust near the O2 sensor. It will suck in air giving the sensor the wrong reading. Use a smoke machine to pump smoke in the exhaust and follow towards motor to find crack. Drop exhaust and reweld and should be good to go.

 

[SAM DACOSTA]

There is probally a crack in the weld on the top side of the exhaust near the O2 sensor. It will suck in air giving the sensor the wrong reading. Use a smoke machine to pump smoke in the exhaust and follow towards motor to find crack. Drop exhaust and reweld and should be good to go.

My 04 had the same issue. it was a crack on the exhaust. Welded and the codes went away. Hope this solves the issue with the original post.