P0175 on the 2022 Lexus IS: Investigating the Rich Condition
The 2022 Lexus IS received a significant refresh with updated styling and the 3.5L 2GR-FKS V6 engine powering the IS 300 AWD (260 hp) and IS 350 (311 hp). The base IS 300 RWD uses the 2.0L 8AR-FTS turbo four-cylinder (241 hp). When P0175 appears, bank 2 is running richer than the 14.7:1 target ratio. On the V6, that's the rear bank near the firewall — a tight space in the IS's compact engine bay that can make diagnosis more involved.
What You'll Notice
- Check engine light on the redesigned gauge cluster
- Fuel economy worse than the IS 350's rated 21/30 MPG
- Black or gray exhaust smoke during hard acceleration
- Rough idle inconsistent with the IS's refined character
- Fuel odor from the exhaust
- Possible hesitation during spirited driving
Primary Causes for the 2022 IS
1. Dirty MAF Sensor
The refreshed IS uses the same proven MAF sensor design that's susceptible to contamination from fine particles, oil residue, and aftermarket intake filter oils. Performance enthusiasts frequently install cold air intakes on the IS, which is the number one source of MAF contamination. The sensor sits in the intake tract upstream of the throttle body. A $10 MAF cleaning spray resolves most cases; OEM Lexus replacement runs $200–$370.
2. A/F Ratio Sensor Wear (Bank 2)
The 2022 IS with moderate mileage (20,000–50,000 miles) can begin showing A/F sensor degradation, especially if the engine has been running rich and contaminating the sensor element. A lazy or biased sensor sends the ECM incorrect mixture data, causing compensatory fuel addition. Replacement costs $250–$470 at a Lexus dealer; $180–$340 independent.
3. D-4S Injection System Issues
The IS 350 and IS 300 AWD use Toyota's D-4S dual injection (port + direct). Carbon buildup on direct injection nozzles or leaking port injectors on the rear bank cause bank-specific rich conditions. D-4S diagnosis requires Techstream software to isolate which injection circuit is contributing. Cleaning costs $180–$320; injector replacement runs $250–$650 depending on the circuit.
4. Canister Purge Valve
The EVAP system's canister purge valve is a known failure point on Toyota/Lexus 2GR engines. When stuck open, it feeds unmetered fuel vapor continuously into the intake. This causes both banks to run rich, but P0175 (bank 2) may trigger first depending on the sensor response timing. The valve costs $45–$80 with $80–$150 labor.
Diagnostic Pathway
- Scan for all codes including pending — look for EVAP codes suggesting a purge valve issue
- Check both bank 1 and bank 2 LTFT values — if both negative, suspect MAF or fuel pressure
- Clean the MAF sensor and clear codes to see if P0175 returns
- If the code returns, analyze A/F sensor waveforms using a professional scan tool
- Perform fuel pressure test — spec is 44–50 psi on the 2GR-FKS
- Check for intake leaks with a smoke machine
Can You Keep Driving?
Short commutes are fine. The IS is a sport sedan designed for enthusiastic driving, but restrain yourself until P0175 is resolved. Rich running during aggressive acceleration punishes the catalytic converters hardest, and on the IS, each converter costs $1,300–$2,400. If you're an IS 500 owner, P0175 doesn't apply since it uses a different V8 engine.
Warranty Status for 2022 Models
Your 2022 IS should still be within the 4-year/50,000-mile basic warranty and well within the 6-year/70,000-mile powertrain warranty. Contact your Lexus dealer to confirm coverage before paying out of pocket. The federal emissions warranty (8 years/80,000 miles) covers key sensors and catalytic converters through 2030.