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Discussion Starter #1
hey guys, I have had the check engine light for the codes P0171/4 for a while now and its been driving me nuts on what could be the problem. It is a 2008 RRS and I have had it for a little bit over a year now. Love my Range but this code is just aching me. I took the car to the RR Dealer to get a diagnostic and they gave me a few things to change like the PCV Valve and driver belts. I changed both and I have also changed the MAF sensor, throttle body, and air filter, and gas cap. What else could be the cause for the code to still be alive and kicking? I do feel a loss of power on the car itself ever since I first got the vehicle, fuel consumption is through the roof as I get about 13mpg lol. But yea anyone know what else could be the cause for the code? I have read the forum post about these codes in particular but it seems like I already swapped out the major parts that were discussed. Thanks in advance to anyone that reaches out!

- Kevin Range Rover Sport 2008

2006-2009 Range Rover Sport
216 Posts
Hi Mike, straight from google'
This code is triggered by the first downstream (front) O2 sensor. The sensor provides a reading of the air:fuel ratio leaving the engine's cylinders, and the vehicles powertrain/engine control module (PCM/ECM) uses that reading and adjusts to keep the engine running at that optimum ratio of 14.7:1. If something is not right and the PCM cannot maintain the 14.7:1 ratio, but rather there is too much air, it triggers this code.

A code P0171 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor
Possible cracked vacuum or PCV line/connection
Faulty or stuck open PCV valve
Failed or faulty oxygen sensor (bank 1, sensor 1)
Sticking/plugged or failed fuel injector Low fuel pressure (possible plugged/dirty fuel filter!)
Exhaust leak between engine and first oxygen sensor

Possible Solutions
A lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include:
Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace/repair as required
Inspect all hoses and connections in the air intake system
Inspect and/or test the intake manifold gaskets for leakage
Check for a dirty fuel filter and proper fuel pressure Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool
If you have access, you may want to run a smoke test

Read more at: OBD-II DTC: P0171 System Too Lean (Bank 1)
Copyright OBD-Codes.com

2006-2009 Range Rover MkIII / L322
572 Posts
We need your fuel trims.
You have to first do a smoke test.
Mostly leaks pcv hose.
If you dont have a leak than check your injectors, coils, sparks.
Bad coils and bad injectors are messing with ecu

2010-2012 Range Rover Sport
337 Posts
Hi guys, I may not have a direct/exact solution for you but let me just throw my 2 cents, may be you can gain something out of it... So recently I had a LR tech replacing injectors+spark plugs and ignition coils. This guy is forman, level 4 tech at JLR... so while he was doing the job I was bored out my mind, he tasked me to clean a throttle body I really took my time as I had plenty, then I offered to clean MAFs... Here what he said: No don't touch MAFs, not now, not ever, I read on FB and other sources that people having air to fuel mix issues in pre 5.0 LRs and start cleaning/replacing MAFs with very short lasting or no results. Here what works: there is a machine that you connect to LR intake to clean the injectors, you remember we did this on your previous RRS? There is a special chemical solution that you use. If you do this as preventative, one bottle if fine but if you're having fuel mixture related codes, you have to go through 2 bottles.
After procedure is done, Check engine will show up once again and go away, and absolute majority of situations, this solves the problem...
He, obviously uses LR proprietary equipment and chemistry and I can not tell you what they are but there are should be similar systems/fluids used by private shops that can run the same procedure.
Again - just a piece of Info I've heard from the person who specializes in JLRs only.
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