2022 RDX Check Engine Light with P0420 Code

ClearTheCode admin answer:

A P0420 code on your 2022 Acura RDX indicates that the catalytic converter on Bank 1 (the side of the engine with cylinder #1) is not operating at peak efficiency. While it often points to the catalytic converter itself, especially at higher mileages, there are other potential causes, especially on a relatively new vehicle like yours.

Here's a breakdown of what P0420 means and what to investigate:

Understanding P0420:

The engine's computer monitors the efficiency of the catalytic converter by comparing readings from the upstream (before the cat) and downstream (after the cat) oxygen sensors. If the downstream sensor's readings start to mirror the upstream sensor's, it indicates the catalyst isn't storing enough oxygen, meaning it's not efficiently converting harmful exhaust gases.

Potential Causes (in order of likelihood for a 2022 model):

1. Oxygen (O2) Sensor Malfunction:

   • Cause: A faulty downstream O2 sensor (or sometimes the upstream) can send incorrect readings to the ECU, falsely triggering the P0420 code. This is more common than a catalytic converter failure on a low-mileage vehicle.
   • Action: A professional diagnostic scan tool can monitor live O2 sensor data to determine if they are switching correctly.

2. Exhaust Leak:

   • Cause: An exhaust leak before the downstream O2 sensor or near the catalytic converter can allow unmetered air into the exhaust stream, skewing O2 sensor readings.
   • Action: Visually inspect the exhaust system for cracks, rust, or loose connections, especially around the manifold and catalytic converter.

3. Engine Misfires/Fuel System Issues:

   • Cause: Persistent engine misfires, running too rich/lean, or burning excessive oil can dump unburnt fuel or contaminants into the catalytic converter, causing it to overheat and fail prematurely.
   • Action: Check for other pending or active diagnostic trouble codes (DTCs) that might indicate misfires (P030x) or fuel system problems.

4. Catalytic Converter Failure:

   • Cause: While less common at 35,000 miles, a catalytic converter can fail due to manufacturing defect, severe engine issues, or contamination.
   • Action: This is usually a last resort diagnosis after ruling out other causes.

When to See a Shop:

Given that your 2022 RDX is still under warranty (powertrain warranty typically covers catalytic converters for 8 years/80,000 miles), your first step should be to take it to an Acura dealership. They have specialized diagnostic equipment to:

• Perform advanced O2 sensor testing.
• Check for any underlying engine issues that might be contributing to the code.
• Confirm if the catalytic converter itself is truly faulty.

Do not ignore this code, as a failing catalytic converter can lead to reduced fuel economy and potential damage to other engine components over time.