What Does P0420 Mean on a 2022 Acura TLX?
A P0420 code on your 2022 Acura TLX indicates the ECM has detected below-threshold efficiency from the catalytic converter. The 2022 TLX offers two engine options: a 2.0L VTEC turbocharged four-cylinder producing 272 horsepower in standard trims, and a 3.0L turbocharged V6 producing 355 horsepower in the Type S. The inline-four has one exhaust bank, while the V6 has two banks with P0420 specifically addressing Bank 1.
Understanding which engine your TLX has is important for accurate diagnosis, as the exhaust configurations differ significantly between the two.
Symptoms
- Check engine light on — The main symptom
- Slight fuel economy change — Barely noticeable in most cases
- Possible sulfur smell — Faint rotten egg odor from exhaust
- Normal driving dynamics — The TLX should handle and accelerate normally
- Emissions test failure — In testing states
Common Causes for the 2022 TLX
1. Downstream O2 Sensor Problem
On the relatively new 2022 TLX, a faulty downstream oxygen sensor is a strong possibility. Both the 2.0L turbo-four and the 3.0L turbo V6 produce high exhaust temperatures that can stress O2 sensors. A sensor that's contaminated, sluggish, or electrically faulty will trigger a false P0420.
2. Software Calibration
Honda and Acura release PCM software updates that refine catalyst monitoring parameters. The 2022 TLX, particularly the new Type S, may benefit from updated calibrations that adjust the sensitivity of the converter efficiency monitoring.
3. Catalytic Converter Issue
While uncommon on a vehicle this new, manufacturing defects can occur. The turbo engines' close-coupled converters operate at extreme temperatures, and any deficiency in the converter's construction will be revealed quickly. Warranty coverage applies.
4. Exhaust Leak
A small leak at the turbo outlet gasket, downpipe connection, or converter flange can introduce ambient air near the O2 sensor. The TLX's sport-oriented exhaust system has multiple connection points that can develop leaks.
Diagnostic Steps
- TSB check — Have your dealer search for applicable Technical Service Bulletins.
- Full code scan — Look for additional diagnostic codes.
- O2 sensor monitoring — Analyze upstream vs downstream waveforms.
- Exhaust inspection — Check all connections and gaskets for leaks.
Repair Costs
- O2 sensor replacement: $140 – $320 (parts and labor)
- Software update: $0 – $150
- Catalytic converter: $1,300 – $2,600 (Type S costs more)
- Exhaust leak repair: $100 – $400
Safe to Drive?
Yes, your 2022 TLX is completely safe with a P0420 code. The sport sedan's handling, braking, SH-AWD, and safety systems are unaffected. Since the 2022 model is under warranty, schedule a dealer visit for the likely no-cost repair.
Prevention
- Use premium fuel — Both TLX engines require premium gasoline
- Follow Acura's maintenance minder — Service when prompted
- Address all engine codes — Don't let small problems damage the converter
- Allow turbo cool-down — After spirited driving, idle briefly before shutting off