What Does P0172 Mean on Your 2022 Acura MDX?
A P0172 code on your 2022 Acura MDX means the powertrain control module (PCM) has detected a rich fuel condition on Bank 1. The 2022 MDX was completely redesigned and is powered by a 3.5L J35Y6 V6 producing 290 horsepower and 267 lb-ft of torque (the Type S gets a 3.0L turbo V6 with 355 hp). Bank 1 on this transverse-mounted V6 is the rear bank closest to the firewall.
A rich condition means there's more fuel in the air-fuel mixture than the ideal 14.7:1 ratio. The PCM uses input from the oxygen sensors and MAF sensor to maintain this balance, and P0172 indicates it can no longer compensate for the excess fuel.
Symptoms You Might Notice
- Check engine light illuminated
- Reduced fuel economy (below the typical 19-26 mpg range)
- Rough or slightly unstable idle
- Fuel smell from the exhaust
- Black soot on exhaust tips
- Occasional hesitation or stumble during acceleration
- Potential misfires at idle
Common Causes of P0172 on the 2022 Acura MDX
- Contaminated MAF Sensor — The mass airflow sensor on the J35 V6 sits in the air intake duct and is susceptible to contamination from dust, debris, or oiled aftermarket air filter residue. This is the most common cause of P0172 on Honda/Acura V6 engines.
- Faulty Front O2 Sensor (Bank 1) — The Bank 1 upstream air-fuel ratio sensor may be sluggish or giving biased readings, causing the PCM to add too much fuel.
- EVAP Purge Valve Stuck Open — A canister purge solenoid that fails in the open position continuously introduces fuel vapors into the intake, enriching the mixture beyond PCM control.
- Leaking Fuel Injector — An injector on Bank 1 that doesn't fully seal can drip fuel into the cylinder, creating a localized rich condition that affects the bank average.
How to Diagnose the Problem
- Scan for all DTCs — Check if P0175 (Bank 2 rich) is also present. Both banks rich suggests a shared cause like MAF sensor or fuel pressure. Bank 1 only suggests an O2 sensor or injector issue.
- Check fuel trim data — LTFT values more negative than -10% on Bank 1 confirm the rich condition. Compare with Bank 2 values.
- Test the MAF sensor — Compare grams-per-second readings against Honda specifications at idle and under load.
- Monitor O2 sensor data — Check Bank 1 Sensor 1 air-fuel ratio sensor for proper operation and response time.
- Test purge valve — Command open and close with a scan tool to verify the solenoid operates correctly.
- Perform injector balance test — Check for uneven fuel delivery across Bank 1 cylinders.
Repair Options and Cost Estimates
The 2022 MDX is a premium SUV, but Acura parts tend to be more affordable than European luxury brands. Independent shops with Honda/Acura expertise offer great value.
- MAF Sensor Cleaning — DIY: $8-$12. Shop: $70-$130.
- MAF Sensor Replacement — Parts: $100-$220, labor: $70-$130. Total: $170-$350.
- O2/Air-Fuel Ratio Sensor Replacement — Parts: $120-$260, labor: $90-$170. Total: $210-$430.
- EVAP Purge Valve Replacement — Parts: $30-$80, labor: $65-$120. Total: $95-$200.
- Fuel Injector Replacement — Parts: $65-$150 each, labor: $180-$380. Total: $245-$530 per injector.
Can You Fix This Yourself?
MAF sensor cleaning is one of the easiest DIY jobs — 10-15 minutes with MAF cleaner spray. O2 sensor replacement is moderate difficulty with jack stands and an O2 sensor socket. The rear bank (Bank 1) on the MDX is harder to access than the front, so plan for some extra time. Injector work requires removing the intake manifold and is best left to a professional.
Prevention Tips
- Replace the engine air filter every 15,000-20,000 miles
- Use top-tier regular gasoline (87 octane is fine for the standard MDX)
- Follow the Acura Maintenance Minder system
- Avoid oiled aftermarket air filters that can contaminate the MAF sensor
- Address warning lights and drivability changes promptly