P0131 on the 2022 Lexus IS
Your 2022 Lexus IS has set code P0131, indicating the Bank 1 Sensor 1 air-fuel ratio sensor is reading below the expected voltage range. The 2022 IS received a significant refresh with updated styling on the same platform. Engine options include the IS 300 RWD (2.0L turbo, 8AR-FTS), IS 300 AWD (3.5L V6, 2GR-FKS), IS 350 (3.5L V6, 2GR-FKS), and the track-focused IS 500 (5.0L V8, 2UR-GSE). On the turbo four-cylinder, there's one bank. On V6 and V8 models, Bank 1 is the rear bank.
What You'll Notice
- Check engine light on
- Slight fuel economy decrease
- Minor idle roughness
- Subtle hesitation during acceleration
- On the IS 500 V8, Bank 1-specific exhaust note change possible
Causes
1. A/F Sensor Failure
The wideband Denso A/F sensor can degrade from thermal stress, contamination, or internal defects. On the IS 300 RWD turbo, high exhaust temperatures downstream of the turbo accelerate wear. On the IS 500's 5.0L naturally aspirated V8, the sensor benefits from more moderate temperatures but higher exhaust volume. Regardless of engine, contamination from PCV system oil vapors or fuel sulfur can poison the sensing elements.
2. Wiring or Connector Problems
The IS's sport sedan design means the sensor harness navigates a tight engine bay. Heat damage to insulation, connector corrosion from moisture exposure, or harness chafing against engine bay components can all cause signal issues. On the IS 500 V8, the larger engine takes up more space, leaving less room for harness routing.
3. Exhaust Leak
Exhaust manifold gasket leaks on the rear bank, or connection leaks at the front pipe joints, can introduce ambient air past the A/F sensor. On the turbo IS 300, the turbo-to-downpipe gasket is a common leak point. On the V6 and V8, check the manifold-to-head gaskets.
4. Lean Fuel Condition
A genuine lean condition from vacuum leaks, fuel delivery issues, or MAF sensor contamination triggers accurate low readings. P0171 alongside P0131 confirms this scenario.
Diagnostic Steps
- Scan all codes and review freeze frame data.
- Monitor A/F sensor pump current live — should respond to throttle changes.
- Compare Bank 1 and Bank 2 data on V6 and V8 models.
- Inspect sensor connector for corrosion or damage.
- Check exhaust connections for leaks.
- Review fuel trims for lean indications.
Repair Costs
Genuine Denso A/F sensor: $140–$340. Dealer labor: $100–$230. Total: $240–$570. The IS 500 V8 may have higher sensor costs due to the specific part number. The 2022 IS should be under the 4-year/50,000-mile warranty and 8-year/80,000-mile emissions warranty. Check with your dealer.
Priority
Fix within two weeks. The IS is a driver-focused sedan that deserves precise engine management. Under warranty, there's no reason to delay.