What Does P0420 Mean on a 2022 Audi Q5?
A P0420 code on your 2022 Audi Q5 means the engine control module has detected that the catalytic converter isn't converting exhaust gases efficiently enough. The 2022 Q5 uses a 2.0L TFSI turbocharged four-cylinder engine producing 261 horsepower, paired with a 7-speed S tronic transmission and standard quattro all-wheel drive. The SQ5 uses a 3.0L TFSI turbocharged V6 producing 349 horsepower. As the standard Q5 has an inline-four, there's one exhaust bank and one main catalytic converter.
The Q5 is one of Audi's best-selling models, and while it's built to high standards, catalytic converter-related codes can still occur. Here's what you need to know.
Symptoms
- Check engine light and MMI alert — The main indicators
- Slight fuel economy drop — Possibly 1-2 MPG
- Faint sulfur smell — From the exhaust area
- Normal driving behavior — The Q5 should drive as expected
- Emissions test failure — In testing states
Common Causes on the 2022 Q5
1. Downstream O2 Sensor Problem
The post-catalyst oxygen sensor on the Q5's 2.0T engine monitors converter efficiency. Premature sensor failure, contamination, or electrical faults can produce incorrect readings that trigger P0420. The turbo engine's high exhaust temperatures create a demanding environment for sensors.
2. Catalytic Converter Issue
The close-coupled catalytic converter operates at extreme temperatures due to its proximity to the turbocharger. Over time or due to manufacturing inconsistencies, the catalyst material can degrade. The Q5's use for family hauling and occasional towing adds thermal stress.
3. ECM Software
Audi releases software updates that refine emissions monitoring parameters. The Q5's catalyst monitoring may benefit from updated calibration data, especially if the original software was overly sensitive.
4. Exhaust Leak
Exhaust leaks at the turbo-to-downpipe connection, converter flanges, or gaskets can introduce false air. The Q5's higher ride height compared to sedans means more exposure to road debris and underbody stress.
Diagnostic Steps
- Audi-specific diagnostics — Use VCDS or dealer-level tools for detailed fault code data.
- TSB check — Have the dealer search for applicable Technical Service Bulletins.
- O2 sensor analysis — Monitor sensor response times and voltage patterns.
- Exhaust inspection — Check all connections from turbo to downstream sensor.
Repair Costs
- O2 sensor: $180 – $400 (Audi OEM parts)
- Catalytic converter: $1,500 – $3,200 for OEM parts and labor
- Software update: $0 – $200
- Exhaust leak repair: $150 – $500
Safe to Drive?
Yes, your 2022 Q5 is safe to drive with P0420. The quattro system, safety features, and driving dynamics are all unaffected. Since the 2022 model should still be under warranty, schedule a dealer visit.
Prevention
- Premium fuel only — The 2.0T requires premium gasoline
- Follow Audi service intervals — Regular maintenance prevents converter issues
- Fix engine codes promptly — Misfires destroy converters
- Use Audi-approved oil — Correct specification prevents carbon buildup