What does P1140 mean on a Chevy?

P1140. HO2S Transition Time Ratio Bank 1 Sensor 2. Applies to Silverado, Sierra, Tahoe, Suburban, Avalanche.

What causes P1140 on a Chevy?

Sluggish Bank 1 Sensor 2 downstream oxygen sensor past its service life Failing catalytic converter masking as a slow rear sensor Exhaust leak between the upstream sensor and the Bank 1 downstream sensor Corroded downstream HO2S connector from road splash

How do I fix P1140 on a Chevy?

Graph Bank 1 Sensor 2 response time on a Tech2 or GDS2 during deliberate mixture variation Check catalyst efficiency data before replacing the rear sensor Inspect the exhaust for leaks between the converter and the downstream sensor Clean and reseat the Bank 1 Sensor 2 connector, then retest response time Replace the downstream sensor only if transitions stay slow with a healthy catalyst

Code

P1140

HO2S Transition Time Ratio Bank 1 Sensor 2

Category: Powertrain - Fuel/Air Metering
Severity: Check Engine Light
Applies to: Silverado, Sierra, Tahoe, Suburban, Avalanche
Related: No single generic twin. See OBD Codes List

What it means

P1140. HO2S Transition Time Ratio Bank 1 Sensor 2. This Chevy-enhanced code applies to Silverado, Sierra, Tahoe, Suburban, Avalanche.

Findings, check these first

Sluggish Bank 1 Sensor 2 downstream oxygen sensor past its service life
Failing catalytic converter masking as a slow rear sensor
Exhaust leak between the upstream sensor and the Bank 1 downstream sensor
Corroded downstream HO2S connector from road splash

Standard procedure

Graph Bank 1 Sensor 2 response time on a Tech2 or GDS2 during deliberate mixture variation
Check catalyst efficiency data before replacing the rear sensor
Inspect the exhaust for leaks between the converter and the downstream sensor
Clean and reseat the Bank 1 Sensor 2 connector, then retest response time
Replace the downstream sensor only if transitions stay slow with a healthy catalyst

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Sources and review

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Last updated 2026-09-19.

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