P0159
Low SeverityO2 Sensor Circuit Slow Response (Bank 2, Sensor 2)
Emissions System
What Does P0159 Mean?
Downstream O2 sensor bank 2 responds too slowly.
Common Fix
Replace O2 sensor
Estimated Cost (DIY)
$25 - $80
Symptoms
- ⚠️Check engine light
- ⚠️Failed emissions
Common Causes
Aging sensorlikely
Contaminationpossible
How to Diagnose P0159
- 1Monitor response rate
- 2Replace if slow
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Frequently Asked Questions
- Is P0159 urgent?
- No — downstream sensors only monitor the cat. No driveability effect.
- How to test response time?
- With scan tool, the downstream voltage should shift within 300ms of upstream changes.