P0140
Low SeverityO2 Sensor Circuit No Activity (Bank 1, Sensor 2)
Emissions System
What Does P0140 Mean?
The downstream O2 sensor on bank 1 shows no voltage changes at all. The sensor is likely dead.
Common Fix
Replace downstream O2 sensor
Estimated Cost (DIY)
$25 - $80
Common Causes
How to Diagnose P0140
- 1Verify sensor is connected
- 2Check heater circuit
- 3Monitor voltage — flat line confirms dead sensor
- 4Replace sensor
OEM Diagnostic Flowchart
Scroll to load technician if/then branches.
Read live data and freeze frame for P0140 to pinpoint the cause before buying parts.
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Related Resources
Repair guides, symptom pages, and wiring diagrams related to P0140.
OEM Manual Evidence
Browse →A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL Denali AWD V8-6.2L Service Manual | Operation CHARM Operation CHARM : Car...
A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL Denali 2WD V8-6.2L Service Manual | Operation CHARM Operation CHARM : Car...
A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL 4WD V8-6.0L Service Manual | Operation CHARM Operation CHARM : Car repair...
A L L Diagnostic Trouble Codes ( DTC ) — 2013 GMC Truck Yukon XL 4WD V8-5.3L Service Manual | Operation CHARM Operation CHARM : Car repair...
Related Symptoms
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Exact Repair Workflows
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Related Codes
General fault with the downstream (post-cat) O2 sensor on bank 1. This sensor monitors catalytic converter efficiency.
The downstream O2 sensor on bank 1 responds too slowly. This can mask catalytic converter degradation.
The heater in the downstream O2 sensor on bank 1 has failed.
Frequently Asked Questions
- Is P0140 urgent?
- Not at all for driveability. The downstream sensor does not affect engine performance. But it will fail emissions.
- Can I just clear P0140?
- You can clear it, but it will return if the sensor is dead. Replace the sensor for a permanent fix.
Related Repair Guides
If your vehicle has triggered P0140, these DIY repair guides may help: