P0136
Low SeverityO2 Sensor Circuit (Bank 1, Sensor 2)
Emissions System
What Does P0136 Mean?
General fault with the downstream (post-cat) O2 sensor on bank 1. This sensor monitors catalytic converter efficiency.
Common Fix
Replace downstream O2 sensor
Estimated Cost (DIY)
$25 - $80
Symptoms
- ⚠️Check engine light
- ⚠️Failed emissions test
- ⚠️No driveability symptoms
Related Symptoms
Common Causes
How to Diagnose P0136
- 1Check sensor connector and wiring
- 2Monitor sensor voltage (should be steady ~0.4-0.6V)
- 3Compare to upstream sensor behavior
- 4Replace if erratic
OEM Diagnostic Flowchart
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Related Resources
Repair guides, symptom pages, and wiring diagrams related to P0136.
OEM Manual Evidence
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Related Symptoms
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Related Codes
Downstream O2 sensor on bank 1 is reading too low. Could indicate a failing sensor or a lean exhaust condition.
Downstream O2 sensor bank 1 is stuck at a high voltage. Usually a failed sensor.
The heater in the downstream O2 sensor on bank 1 has failed.
Frequently Asked Questions
- Does the downstream O2 sensor affect performance?
- No — it only monitors the catalytic converter. Performance and fuel economy are not affected.
- What should downstream O2 voltage be?
- A healthy downstream O2 should read a fairly steady 0.4-0.7V. Rapid oscillation like the upstream sensor indicates a failing catalytic converter.
Related Repair Guides
If your vehicle has triggered P0136, these DIY repair guides may help: