What Does P0172 Mean on Your 2022 Mitsubishi Outlander?
The P0172 trouble code on your 2022 Mitsubishi Outlander tells you that the engine control module has detected a rich air-fuel mixture on Bank 1. The 2022 Outlander features a 2.5-liter inline-four cylinder engine producing 181 horsepower in the base model, or a 2.5-liter four-cylinder paired with a plug-in hybrid system in the PHEV variant. Both use multipoint fuel injection and rely on precise fuel metering for efficiency and emissions compliance.
When the fuel mixture goes rich, the engine is burning more fuel than it needs. This leads to wasted gas, higher emissions, and potential damage to the catalytic converter if the problem persists. The good news is that P0172 is one of the more common OBD-II codes, and the fix is often straightforward and affordable.
Symptoms You Might Experience
- Check engine light illuminated
- Decreased gas mileage
- Black smoke coming from the tailpipe
- Rough or uneven idle
- Strong fuel smell from the exhaust
- Engine hesitation or stumbling
Common Causes of P0172 on the Outlander
- Dirty or Failing MAF Sensor - The mass airflow sensor is often the first suspect. When it gets dirty or starts to fail, it sends incorrect airflow readings to the ECM, which responds by adding more fuel than necessary.
- Faulty Oxygen Sensor - The upstream O2 sensor on Bank 1 monitors exhaust gases and helps the ECM fine-tune fuel delivery. A failing sensor can send skewed data that leads to over-fueling.
- Leaking Fuel Injector - An injector that does not close completely allows fuel to dribble into the cylinder, enriching the mixture beyond what the ECM intends.
- Clogged Air Filter - A severely restricted air filter limits airflow to the engine, which can cause a rich condition since the same amount of fuel is injected with less air available.
How to Diagnose P0172
- Scan for codes - Use an OBD-II scanner to confirm P0172 and check for any companion codes that may point to a specific component.
- Check fuel trims - Monitor short-term and long-term fuel trims with a scan tool. Large negative values on Bank 1 confirm the ECM is actively reducing fuel to compensate for a rich condition.
- Inspect the air filter - Pull the air filter and check its condition. A clogged filter is an easy and inexpensive fix.
- Clean or test the MAF sensor - Remove the MAF sensor and clean it with dedicated MAF cleaner. If cleaning does not resolve the issue, test the sensor output with a scan tool or multimeter.
- Test the O2 sensor - Use a scan tool to watch the upstream O2 sensor voltage. It should switch between roughly 0.1V and 0.9V steadily. A sensor stuck high indicates a rich reading.
Repair Costs for the 2022 Outlander
The Outlander is a mainstream SUV, so repair costs are generally reasonable compared to luxury brands.
- Air filter replacement - $15 to $30 for the filter. A two-minute DIY job.
- MAF sensor cleaning - $10 to $25 for cleaner spray.
- MAF sensor replacement - $100 to $220 for the part, plus $60 to $120 in labor.
- O2 sensor replacement - $80 to $200 for the sensor, plus $80 to $150 in labor.
- Fuel injector replacement - $60 to $150 per injector, plus $150 to $300 in labor.
DIY Feasibility
Many of these repairs are very doable at home. Replacing the air filter requires no tools at all. Cleaning or replacing the MAF sensor takes basic hand tools and about 15 minutes. O2 sensor replacement is a bit more involved but manageable with an O2 sensor socket. Fuel injector replacement is more complex and may require removing the fuel rail, so it is better suited for experienced DIYers or a shop.
Prevention Tips
- Replace the engine air filter every 15,000 to 30,000 miles or as recommended in your owner's manual
- Use quality fuel from reputable gas stations
- Follow the Mitsubishi maintenance schedule for spark plugs and fuel system service
- Do not ignore the check engine light, as prolonged rich running damages the catalytic converter
- Avoid aftermarket air filters that use heavy oil coatings, as they can contaminate the MAF sensor