What Does P0420 Mean on a 2022 Acura MDX?
A P0420 code on your 2022 Acura MDX indicates the engine control module has detected below-threshold efficiency from the Bank 1 catalytic converter. The 2022 MDX features a 3.5L V6 engine producing 290 horsepower in the standard model, while the MDX Type S uses a 3.0L turbocharged V6 producing 355 horsepower. Both engines use a V-configuration with two exhaust banks, and P0420 specifically addresses the Bank 1 catalyst performance.
The 2022 MDX is built on Acura's new platform with updated powertrain technology, so understanding the specific exhaust configuration is important for accurate diagnosis.
Common Symptoms
- Check engine light on — The primary and often only symptom
- Slight fuel economy decrease — Possibly 1-2 MPG less than normal
- Faint sulfur exhaust odor — Rotten egg smell near the tailpipe
- Normal driving experience — The MDX typically drives fine
- Emissions test failure — Automatic fail in testing states
Common Causes on the 2022 MDX
1. Downstream O2 Sensor Problem
On a relatively new vehicle like the 2022 MDX, a faulty downstream oxygen sensor is a top suspect. The Bank 1 Sensor 2 O2 sensor monitors converter output, and premature failure or contamination can cause false P0420 readings. Honda/Acura O2 sensors are generally reliable but not immune to early failure.
2. Catalytic Converter Defect
The redesigned 2022 MDX's exhaust system is a new design. Manufacturing defects in the converter, while uncommon, can cause early efficiency problems. Issues like insufficient catalyst coating or substrate damage during assembly would be covered under warranty.
3. Exhaust Leak
A small exhaust leak between the engine and the downstream O2 sensor introduces ambient air that skews sensor readings. Check the exhaust manifold gaskets, converter inlet connections, and any flex pipe joints for signs of leaking.
4. Engine Running Condition
If the MDX's V6 or turbo V6 is running rich or lean due to a faulty upstream O2 sensor, air-fuel ratio sensor, or fuel delivery issue, the catalytic converter can become contaminated or overwhelmed over time. Look for companion codes related to fuel trim.
Diagnostic Steps
- Full diagnostic scan — Check for additional codes that might reveal the root cause.
- O2 sensor data review — Compare Bank 1 upstream and downstream sensor waveforms.
- Acura TSB check — Have your dealer check for any Technical Service Bulletins for the 2022 MDX.
- Exhaust system inspection — Visual check for leaks, damage, and loose connections.
Repair Costs
- Catalytic converter replacement: $1,300 – $2,600. The Type S turbo model converters are more expensive.
- Downstream O2 sensor: $140 – $320 including labor
- Exhaust leak repair: $100 – $400
- Engine running condition repair: $200 – $500
Safe to Drive?
Yes, your 2022 MDX is safe to drive with P0420. The three-row luxury SUV will continue to function normally for daily driving, family duties, and commuting. Since it's still under warranty, schedule a dealer visit for a likely no-cost repair.
Prevention Tips
- Use quality fuel — Top Tier gasoline keeps the engine and exhaust clean
- Follow Acura's maintenance schedule — Regular service prevents converter-damaging issues
- Address other codes promptly — Misfires and fuel system problems accelerate converter failure
- Use recommended oil — Proper oil reduces engine deposits that contaminate converters