The P0423 code on your 2022 Lexus RX indicates that the heated catalytic converter on bank 1 is not meeting efficiency standards. Heated catalysts include internal heating elements to reach operating temperature faster, and this code monitors their specific performance.
Heated Catalyst Technology
Some vehicles use electrically heated catalysts (EHC) to reduce cold-start emissions. The heating element brings the catalyst to light-off temperature faster than exhaust heat alone. P0423 indicates this catalyst, despite its heating assistance, isn't converting pollutants efficiently.
Lexus RX Configuration
The 2022 RX offers the RX 350 (3.5L V6) and RX 450h (3.5L hybrid). On V6 engines, bank 1 contains cylinders 1-3-5 (typically passenger side). The sophisticated exhaust systems may include heated elements for emissions compliance, especially in hybrid models.
Causes of Heated Catalyst Issues
The catalyst substrate may be degraded regardless of heating capability. The heating element may have failed, affecting warmup performance. Normal catalyst contamination or poisoning affects efficiency. Engine problems that damage regular catalysts affect heated ones equally.
Diagnostic Approach
Use Lexus Techstream to monitor catalyst efficiency and heating system operation. Verify the heating element functions if equipped. Test oxygen sensors for accurate readings. Check for underlying engine problems. Heated catalyst systems are complex—dealer diagnosis may be appropriate.