What P0172 Means on Your 2022 Mitsubishi Eclipse Cross
If your 2022 Mitsubishi Eclipse Cross is showing a P0172 code, the engine control module has detected that Bank 1 is running too rich, meaning there is more fuel in the air-fuel mixture than there should be. The 2022 Eclipse Cross is equipped with a 1.5-liter turbocharged four-cylinder engine producing 152 horsepower and 184 lb-ft of torque, paired with a CVT transmission. This small-displacement turbo engine relies heavily on accurate sensor readings for proper fuel delivery.
A rich-running condition means wasted fuel, increased emissions, and the potential for long-term damage to expensive components like the catalytic converter. The sooner you track down the cause, the less it will cost you in the long run.
Common Symptoms
- Check engine light illuminated
- Noticeable drop in fuel economy
- Dark or black exhaust smoke
- Rough or irregular idle
- Fuel smell from the tailpipe
- Possible engine hesitation or misfires
Top Causes of P0172 on the Eclipse Cross
- Dirty or Malfunctioning MAF Sensor - The mass airflow sensor is critical for the ECM to calculate the correct fuel amount. On the Eclipse Cross's turbocharged 1.5-liter, a dirty MAF sensor is the leading cause of a rich condition. Oil mist from the turbo system or a contaminated air filter can coat the sensor element.
- Failing Upstream O2 Sensor - The Bank 1 upstream oxygen sensor sends exhaust gas data to the ECM for fuel trim corrections. A degraded or sluggish sensor can cause the ECM to over-fuel the engine.
- Leaking Fuel Injector - A fuel injector that fails to seal properly drips fuel into the cylinder, enriching the mixture beyond what the ECM commands.
- Boost Leak or Intake Issue - The turbo system uses pressurized air. A leak in the charge piping between the turbo, intercooler, and throttle body can cause the MAF sensor to report inaccurate airflow, leading to fueling errors.
How to Diagnose the Issue
- Pull all DTCs - Scan for all stored and pending codes. Related codes like P0101, P0175, or boost-related codes can help narrow the diagnosis.
- Review fuel trims - Use a scan tool to monitor STFT and LTFT on Bank 1. Negative values beyond -10% confirm the ECM is actively cutting fuel to compensate for a rich condition.
- Inspect the air filter - A clogged air filter restricts airflow. Check it first since it is free to inspect and cheap to replace.
- Clean the MAF sensor - Remove and clean the MAF with dedicated MAF sensor cleaner spray. Allow it to dry fully before reinstalling. Clear the code and test drive.
- Check turbo boost plumbing - Inspect all intercooler hoses, clamps, and connections for cracks or loose fittings. A boost leak can throw off MAF readings significantly.
Repair Costs for the Eclipse Cross
The Eclipse Cross is a budget-friendly compact crossover, and repair costs reflect its accessible pricing.
- Air filter replacement - $12 to $25 for the filter. Takes under five minutes.
- MAF sensor cleaning - $10 to $25 for cleaner spray.
- MAF sensor replacement - $90 to $200 for the part, plus $50 to $100 in labor.
- O2 sensor replacement - $70 to $180 for the sensor, plus $70 to $130 in labor.
- Fuel injector replacement - $50 to $120 per injector, plus $120 to $250 in labor.
- Boost hose repair - $20 to $80 for a hose, plus $50 to $150 in labor.
Can You Fix This at Home?
Many of these repairs are well-suited for DIY work. Air filter replacement is the simplest job possible. MAF sensor cleaning takes a screwdriver and 10 minutes. O2 sensor replacement is doable with an oxygen sensor socket and some penetrating oil. Checking boost hoses just requires a visual inspection and possibly tightening clamps. Fuel injector replacement is the most involved repair on this list and may require removing the fuel rail, so less experienced DIYers may want professional help for that one.
Prevention Tips
- Replace the engine air filter every 15,000 to 30,000 miles
- Use quality gasoline from reputable stations
- Avoid over-oiled aftermarket air filters that can contaminate the MAF sensor
- Inspect turbo boost hoses during routine maintenance
- Follow the Mitsubishi maintenance schedule for spark plug replacement