If your Honda Pilot’s check engine light is on and the code is P0175, you’re dealing with a specific fuel system issue. The P0175 Honda Pilot code means your vehicle’s engine computer has detected that the fuel mixture is too rich on bank 2. In simpler terms, too much fuel or not enough air is entering one side of your engine.
This guide will help you understand what causes this, how to diagnose it yourself, and the steps to fix it. We’ll break down the technical jargon into simple, actionable advice. You can save time and money by following a logical process.
P0175 Honda Pilot
The P0175 code stands for “System Too Rich (Bank 2).” Every modern car, including your Pilot, has an engine computer (PCM) that constantly monitors the air-fuel ratio. It uses sensors, primarily the oxygen (O2) sensors, to check if the mixture is perfect. A “rich” condition means the mix has too much gasoline. “Bank 2” refers to the side of the engine that does not contain cylinder number 1. On most Honda V6 engines, Bank 2 is usually the rear bank of cylinders (closer to the firewall).
What Does “Too Rich” Actually Mean for Your Car?
A rich running condition hurts your Pilot in several ways. You’ll likely notice poor fuel economy, as you’re burning more gas than needed. The engine may run rough, hesitate during acceleration, or even smell like rotten eggs (sulfur) from the exhaust. In severe cases, it can damage the catalytic converter, a very expensive part to replace. Ignoring a P0175 code is not a good idea.
Common Symptoms of the P0175 Code
You might experience one or more of these signs before or after the check engine light appears:
- Illuminated check engine light (sometimes flashing under heavy load).
- Reduced gas mileage.
- Rough idle or shaky engine.
- Black smoke coming from the exhaust pipe.
- A strong fuel smell or sulfur smell from the exhaust.
- Lack of power when you press the accelerator.
Main Causes of a P0175 in Your Honda Pilot
The problem usually boils down to a few key areas. Extra fuel is getting into the combustion chamber, or not enough air is getting in to balance it out. Here are the most frequent culprits, starting with the most common.
Faulty or Dirty Mass Air Flow (MAF) Sensor
The MAF sensor measures the amount of air entering the engine. If it’s dirty or broken, it can send a wrong signal to the PCM. The computer might think less air is coming in than actually is, and inject too much fuel in response, causing a rich condition. This is often the first thing to check.
Defective Oxygen (O2) Sensors
The O2 sensors downstream of the catalytic converter monitor the exhaust to tell the PCM how well it’s managing the fuel mix. A lazy or faulty O2 sensor on Bank 2 can send a constant “rich” signal, even when the mixture is fine, tricking the computer into logging the P0175 code.
Leaking or Stuck Fuel Injectors
Fuel injectors spray a precise mist of gasoline into the engine. If an injector on Bank 2 is leaking or stuck open, it will dump too much fuel into its cylinder. This directly creates a rich condition on that bank of the engine. Dirty fuel injectors can sometimes stick open.
Problems with the Fuel Pressure Regulator
This component maintains proper fuel pressure in the system. A failing regulator can allow too much pressure, forcing extra fuel through the injectors. This affects the whole engine, but might be diagnosed as a Bank 2 issue first depending on sensor readings.
Clogged or Dirty Air Filter
A extremely dirty air filter can restrict airflow into the engine. Less air leads to a relatively richer fuel mixture. While this usually affects both banks, other factors can make it show up as a Bank 2 code. It’s a simple and cheap thing to check.
Failing Engine Coolant Temperature (ECT) Sensor
The PCM uses the ECT sensor to know if the engine is cold or warm. A cold engine needs more fuel. If the sensor is faulty and always reports a cold engine, the computer will keep adding extra fuel, creating a rich condition.
Vacuum Leaks (Less Common, But Possible)
While vacuum leaks typically cause a lean code (too much air), a significant leak on only one bank could potentially confuse the O2 sensor readings and lead to a rich diagnosis from the PCM. It’s less likely but worth considering if other causes are ruled out.
Step-by-Step Diagnostic Guide
Follow these steps in order to find the root cause. You’ll need a basic OBD2 scanner and some common hand tools.
- Clear the Code and Test Drive: Use your scanner to clear the P0175 code. Take the car for a drive to see if it comes back immediately. If it does, the problem is current and active. If it takes a while, the issue might be intermittent.
- Check for Other Codes: Look at your scanner for any other stored codes. A P0172 (System Too Rich, Bank 1) or fuel trim data can give you more clues. Codes related to the MAF or O2 sensors are big hints.
- Inspect the Air Filter and Intake: Open the air box and look at the filter. If it’s filthy, replace it. Visually check the air intake hose for cracks or loose connections that could cause unmetered air issues.
- Clean the MAF Sensor: Locate the MAF sensor in the air intake tube. Carefully unplug it and remove it. Spray it thoroughly with CRC MAF sensor cleaner (only use this specific cleaner). Let it dry completely before reinstalling. This fixes many problems.
- Look at Live Data:
With the engine running and your scanner in live data mode, check the Long Term Fuel Trim (LTFT) for Bank 2. A consistently negative number (e.g., -10% to -25%) confirms a rich condition. Also, watch the Bank 2 O2 sensor voltage. A voltage stuck high (above 0.7V) suggests a rich exhaust.
- Check for Vacuum Leaks: Listen for hissing sounds around the engine, especially near the intake manifold on Bank 2. You can use a can of carburetor cleaner and spray around hoses and gaskets (with the engine running). If the engine RPM changes, you’ve found a leak.
- Test Fuel Pressure: You’ll need a fuel pressure gauge. Connect it to the fuel rail test port. Compare your reading with the factory specification (usually around 50-60 PSI for Hondas). If pressure is too high, the regulator or fuel pump may be faulty.
- Swap Components (Advanced): If you’re still stuck, you can try swapping the Bank 1 and Bank 2 upstream O2 sensors. If the code moves to Bank 1 (P0172), you know the original Bank 2 sensor is bad. This method works for other parts like fuel injectors if you’re careful.
Repair Instructions and Fixes
Once you’ve identified the likely cause, here’s how to adress it.
How to Replace a MAF Sensor
- Disconnect the negative battery terminal for safety.
- Unplug the electrical connector on the MAF sensor.
- Use a screwdriver to loosen the hose clamp holding the sensor in the intake tube.
- Gently pull the sensor out.
- Install the new sensor, tighten the clamp, reconnect the plug, and reconnect the battery.
How to Replace an Oxygen Sensor
You’ll need a special O2 sensor socket. Apply penetrating oil to the old sensor threads beforehand and let it soak.
- Locate the faulty O2 sensor (on the exhaust manifold or downpipe for Bank 2).
- Disconnect its electrical plug.
- Use the O2 sensor socket and a ratchet to carefully loosen and remove the old sensor.
- Thread the new sensor in by hand first to avoid cross-threading, then tighten with the socket.
- Reconnect the electrical plug.
Cleaning Fuel Injectors
You can try a fuel system cleaner additive like Techron in your gas tank. For a deeper clean, you may need to have them professionally ultrasonically cleaned or replace leaky ones, which is a more involved job requiring removal of the fuel rail.
Prevention Tips
To avoid a P0175 code in the future, stick to a regular maintenance schedule. Replace your air filter as recommended. Use good quality fuel and consider a fuel injector cleaner every few oil changes. Be careful when cleaning your engine bay; avoid spraying water directly at electrical sensors like the MAF.
When to See a Professional Mechanic
If you’ve gone through the diagnostics and aren’t comfortable with the repairs, it’s time to call a pro. This is especially true for internal vacuum leaks, fuel pressure problems, or if you suspect a failing PCM (which is rare). A mechanic has advanced tools to pinpoint the issue quickly.
FAQ Section
Is it safe to drive my Honda Pilot with a P0175 code?
You can likely drive for a short time, but you should adress it soon. Driving for weeks can damage the catalytic converter. If the engine is running very poorly or the light is flashing, avoid driving it.
Can a bad spark plug cause a P0175 code?
Not directly. A bad spark plug might cause a misfire, which can lead to unburned fuel in the exhaust. This might make the O2 sensor read a rich condition, but you would usually get a misfire code along with it.
How much does it cost to fix a P0175 code?
Costs vary widely. A new MAF sensor is $100-$250. An O2 sensor is $75-$200. Labor adds $100-$200. If it’s a simple fix like cleaning the MAF, it might cost almost nothing. A major issue like injectors could cost $500+.
What’s the difference between P0175 and P0172?
They both mean “System Too Rich.” P0175 is for Bank 2, and P0172 is for Bank 1. The diagnostic process is identical, just focused on the opposite side of the engine.
Can a dirty throttle body cause P0175?
A very dirty throttle body can disrupt airflow, but it usually affects the whole engine. It’s more likely to cause idle problems than a single-bank rich code. It’s still a good thing to clean during maintenance.
Dealing with a P0175 code in your Honda Pilot requires patience and a methodical approach. Start with the simple and free checks, like the air filter and MAF sensor cleaning. Use live data from a scanner to guide you. By understanding the common causes and following the diagnostic steps, you can identify the problem and get your Pilot running smoothly and efficiently again. Remember, fixing this code not only turns off the check engine light but also restores your fuel economy and protects your engine from further damage.