Range Rover system too lean – code P0171 / P0174

The Range Rover system too lean, P0171 and P0174 codes indicate a low fuel trim or lean fuel condition in the engine, which means there is too much air and not enough fuel in the mixture.

If your Land Rover Range Rover is throwing up a dreaded orange ‘check engine light‘ and you have scanned it to find codes P0171 or P0174, don’t get too worried yet! These codes indicate a low fuel trim, meaning your engine is running lean.

In other words, the mixture has too much air and insufficient fuel. If ignored, this can cause restricted engine performance, decreased fuel efficiency, and can even damage the catalytic converter!

In this article, we will go over some basic checks and diagnoses to see if you can fix it before having to take your Range Rover into the garage and spend a lot of money.

What models are affected?

• Land Rover Defender
• Range Rover Discovery
• Range Rover Evoque
• Range Rover Sport
• Range Rover Velar
• Range Rover Vogue

Common causes leading to this error code

Check all the following steps, and sometimes you can get away with easy fixes before taking your beloved Range Rover into your local mechanic’s garage. Remember, use a Land Rover Approved Garage, amateurs or guys that don’t work on these jeeps regularly are not worth the risk!

1. Check the airbox and air filter

First, you will want to locate the airbox under the hood. The air filter is located in this area, where the engine gets the air to breathe. A clogged or dirty air filter can cause a lean fuel condition and trigger a P0171 or P0174 code.

Make sure to check the air filter and replace it if necessary. Simple ways to know if you need to replace the air filter are the obvious, extremely dirty, rips or holes. You can use a hoover/vacuum on the filter to clean it as a stop-gap, so you should buy a new one if it looks worse for wear.

2. Check the pipe to the engine and mass airflow sensor

Next, you will want to check the snorkel that goes directly into the engine. Make sure it is tight and not loose. You will also find a mass airflow sensor (MAF) near the air filter. See the above image.

This sensor tells the Range Rover’s computer how much air is getting into the engine and helps the computer determine how much fuel to inject. If this sensor is malfunctioning, it can cause a lean fuel condition.

If the mass air flow sensor starts to fail, it can occasionally throw this code up on your Ranger Rover’s dashboard. I would highly recommend either cleaning your MAF to see if it throws these codes up again or not and if it doesn’t, then I would recommend buying a brand new one as cleaning a MAF is only a stopgap as they wear over time and will break down again.

3. Check for loose hoses or connections

Also, check for any disconnected hoses or loose connections around the air filter, mass airflow sensor, and intake. If any pipes or hoses look loose, try tightening them up and run another OBD reading.

These can cause a lean fuel condition and trigger a P0171 or P0174 code.

Make sure to check for any cracks in the rubber components and replace them if necessary.

4. Check underneath the engine cover and intake hoses

Many vehicles also have little covers over the engine that can be lifted up to check for any disconnected hoses or loose connections. Check the hoses connected to the intake and make sure everything is attached. If you had recent engine work done, check for any disconnected hoses.

5. Check for open ports

If none of the above steps resolves the issue, it may be necessary to perform further diagnosis. Consult a mechanic or mechanic’s manual for specific instructions for your vehicle. Also, consider checking for any other codes or issues that may be present in addition to P0171 and P0174.

Consider having a professional mechanic inspect the fuel system, including the fuel pump, fuel filter, and fuel pressure regulator. Additionally, check for vacuum leaks in the intake or exhaust system, check for proper operation of the engine’s sensors and consider having a professional perform a smoke test to check for vacuum leaks.

Additional Steps to Take

1. Further diagnosis may be necessary: If the above checks do not resolve the issue, further diagnosis may be necessary.
2. Check for other codes or issues: Consider checking for any other codes or issues that may be present in addition to P0171 and P0174.
3. Inspect the fuel system: Consider having a professional inspect the fuel system, including the fuel pump, fuel filter, and fuel pressure regulator.
4. Check for vacuum leaks: Check for vacuum leaks in the intake or exhaust system.
5. Check the engine’s sensors: Check for proper operation of the engine’s sensors, including the oxygen sensor, throttle position sensor, and mass airflow sensor.
6. Perform a smoke test: Consider having a professional perform a smoke test to check for vacuum leaks.
7. Consult a mechanic: Consult a mechanic or mechanic’s manual for specific instructions for your vehicle.

Summary

In conclusion, it is important to address a P0171 or P0174 code as soon as it is detected to prevent further damage to the vehicle. While the above steps can be a good starting point, it is always best to consult a professional if the issue cannot be resolved.

Remember, a lean fuel condition can cause poor engine performance, decreased fuel efficiency, and damage to the catalytic converter. So, don’t hesitate to get the issue fixed as soon as possible.

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