What the P0420 Code Means on Your 2022 Acura RDX
A P0420 code on your 2022 Acura RDX tells you that the engine control module has detected reduced efficiency from the catalytic converter. The 2022 RDX is powered by a 2.0L turbocharged four-cylinder engine producing 272 horsepower — the same VTEC Turbo unit used across several Honda and Acura products. Since this is an inline-four engine, there's only one exhaust bank, making P0420 the relevant catalyst efficiency code.
The turbocharged engine creates higher exhaust temperatures than naturally aspirated engines, which affects both the catalytic converter and O2 sensor operation. Let's explore the likely causes.
Symptoms
- Check engine light illuminated — The most visible symptom
- Marginal fuel economy drop — Possibly 1-2 MPG less
- Possible sulfur exhaust smell — Rotten egg odor
- Normal driving performance — The RDX should drive as expected
- Emissions test failure — In states that test
Common Causes on the 2022 RDX
1. Downstream O2 Sensor Issue
On the RDX's 2.0L turbo engine, the downstream O2 sensor operates in a very hot environment. Premature sensor failure or contamination can cause false P0420 readings. Since the turbo engine's catalytic converter is close-coupled to the turbocharger, the sensor sees extreme temperatures that can shorten its life.
2. Catalytic Converter Degradation
The close-coupled catalytic converter in the turbo exhaust path operates at very high temperatures. Over time, this thermal stress can cause the catalyst substrate to degrade faster than on naturally aspirated engines. Higher-mileage RDX models or those driven aggressively are more susceptible.
3. Exhaust Leak
The turbocharged exhaust system has several connection points — turbo outlet, downpipe flanges, and converter connections. Any leak at these points introduces false air that can trigger P0420. Check the turbo-to-downpipe gasket and converter inlet flange particularly.
4. PCM Software Issue
Honda and Acura periodically release PCM software updates that adjust catalyst monitoring parameters. A calibration issue can cause premature P0420 codes. Your dealer can check for and apply any available updates.
Diagnostic Steps
- Check for TSBs — Honda/Acura TSBs may address this specific issue.
- Full code scan — Look for additional codes that may point to the root cause.
- O2 sensor data analysis — Compare upstream and downstream sensor patterns.
- Exhaust system inspection — Focus on turbo and converter connections.
Repair Costs
- Downstream O2 sensor: $130 – $300 (parts and labor)
- Catalytic converter replacement: $1,200 – $2,200 for OEM parts
- Exhaust leak repair: $100 – $400
- PCM software update: $0 – $150
Safe to Drive?
Yes, your 2022 RDX is safe to drive with a P0420 code. The code doesn't affect safety, SH-AWD operation, or basic drivability. Since the 2022 model should still be under warranty, schedule a dealer visit for a potentially cost-free repair.
Prevention Tips
- Use premium fuel — The turbo engine benefits from higher-octane gasoline
- Follow Acura's maintenance schedule — Regular service prevents converter issues
- Don't ignore misfires — Fix engine running problems quickly
- Allow turbo cool-down — After hard driving, idle briefly before shutting off