A steady check engine light with P0420 on your 2022 Volvo S60 points toward catalytic converter efficiency concerns. Before assuming the worst about your Swedish sport sedan's emissions system, understanding what P0420 measures—and what else can trigger it—helps approach diagnosis sensibly.
Understanding P0420
Code P0420 indicates "Catalyst System Efficiency Below Threshold Bank 1." The engine computer compares readings from upstream and downstream oxygen sensors. When the downstream sensor shows too much activity, it suggests the converter isn't fully cleaning exhaust gases.
Why P0420 on a 2022?
Genuine converter failure on such a new vehicle is uncommon. On a 2022 S60, P0420 more likely indicates sensor issues, exhaust leaks, or running problems affecting the converter—not the converter itself failing from wear.
Typical Symptoms
- Check engine light on steady
- Usually no drivability symptoms
- Possible slight sulfur smell
- Failed emissions test where applicable
- Slight fuel economy decrease possible
Possible Causes
Downstream Oxygen Sensor Failure
The sensor monitoring converter efficiency can fail, reporting false readings that trigger P0420 with a perfectly functional converter.
Exhaust Leaks
Leaks near sensors introduce fresh air that skews readings, potentially triggering efficiency codes without actual problems.
Engine Running Issues
Misfires or rich running send unburned fuel to the converter, potentially damaging it or triggering codes.
Recent Short Trips Only
Converters need operating temperature. Exclusively short trips may prevent proper operation.
Repair Costs
| Repair | Parts | Labor | Total |
|---|---|---|---|
| Downstream O2 sensor | $150-$300 | $100-$200 | $250-$500 |
| Exhaust leak repair | $50-$200 | $150-$300 | $200-$500 |
| Catalytic converter | $1,200-$2,500 | $300-$500 | $1,500-$3,000 |
Warranty Coverage
Federal emissions warranty covers catalytic converters for 8 years/80,000 miles. Your 2022 S60 is well within coverage if the converter is genuinely defective.