P0140 on Chevrolet vehicles
Post-Cat O2 Sensor No Activity (Bank 1 Downstream) — what it means on a Chevrolet, whether it's safe to drive, and the fixes by model and year.
P0140 on a Chevrolet means post-cat o2 sensor no activity (bank 1 downstream). Most vehicles stay drivable short-term, but diagnose it promptly. The most common cause is open circuit in the o2 signal or ground wire (typically $80–$350). Pick your Chevrolet model below for its known failure patterns, recalls, and TSBs.
What does P0140 mean on a Chevrolet?
P0140 is set when the Bank 1 downstream oxygen sensor shows no meaningful activity at all. The voltage sits flat — typically parked at the ECM's bias voltage of roughly 0.4–0.5 V — and never moves, even under conditions that should force it to move. Bank 1 is the bank containing cylinder number 1, and Sensor 2 is the sensor after the catalytic converter. P0140 is different from a sensor reading too low (P0137) or too high (P0138): with no activity the ECM is effectively looking at an open circuit or a completely dead sensor element.
P0140 is a standardized OBD-II code, so its definition is the same on every Chevrolet. What differs by model and engine is which cause is most likely — pick your Chevrolet model below for a diagnosis tuned to its known failure patterns, recalls, and TSBs.
Is it safe to drive a Chevrolet with P0140?
In most cases a Chevrolet stays drivable for short trips with P0140 active, but diagnose and repair it promptly. This is a moderate-severity code — ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on the model and engine.
What causes P0140 on a Chevrolet?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Open circuit in the O2 signal or ground wire | Most common | $80–$350 |
| Failed Bank 1 downstream O2 sensor (dead element) | Most common | $150–$450 |
| Failed sensor heater leaving the sensor below operating temperature — A zirconia sensor produces no signal until it is hot — a dead heater looks exactly like a dead sensor. | Common | $150–$450 |
| Blown O2 heater fuse | Common | $5–$30 |
| Corroded or disconnected downstream O2 sensor connector | Common | $30–$200 |
| Harness chafed or melted against the exhaust | Common | $80–$350 |
| Failed PCM input for the downstream sensor circuit | Rare | $400–$1,500 |
Repair costs are typical US ranges and vary by Chevrolet model, model year, and labor rate. A diagnostic trouble code is a symptom, not a guaranteed failed part — confirm the root cause before replacing anything.
P0140 by Chevrolet model
Select your Chevrolet model and year for a P0140 diagnosis tuned to that vehicle's failure patterns, recalls, and TSBs.
Chevrolet Silverado 1500
1,648 NHTSA owner complaints · 14 recalls on record across the years covered below.
Chevrolet Equinox
1,100 NHTSA owner complaints · 8 recalls on record across the years covered below.
Chevrolet Tahoe
518 NHTSA owner complaints · 11 recalls on record across the years covered below.
Chevrolet Malibu
1,697 NHTSA owner complaints · 8 recalls on record across the years covered below.
Chevrolet Traverse
795 NHTSA owner complaints · 9 recalls on record across the years covered below.
Chevrolet Trax
117 NHTSA owner complaints · 3 recalls on record across the years covered below.
Complaint and recall counts are NHTSA totals for the model years covered on this site, not counts specific to P0140.
P0140 on other makes
Other codes on Chevrolet vehicles
P0140 on a Chevrolet: frequently asked questions
What does diagnostic trouble code P0140 mean on a Chevrolet?
P0140 is set when the Bank 1 downstream oxygen sensor shows no meaningful activity at all. The voltage sits flat — typically parked at the ECM's bias voltage of roughly 0.4–0.5 V — and never moves, even under conditions that should force it to move. Bank 1 is the bank containing cylinder number 1, and Sensor 2 is the sensor after the catalytic converter. P0140 is different from a sensor reading too low (P0137) or too high (P0138): with no activity the ECM is effectively looking at an open circuit or a completely dead sensor element. P0140 is a standardized OBD-II code, so the definition is the same on every Chevrolet — which cause is most likely varies by model and engine.
What are the symptoms of P0140 on a Chevrolet?
Check Engine Light is illuminated. Catalyst readiness monitor will not complete. Often no drivability symptoms at all. Possible slight reduction in fuel economy. Vehicle will fail emissions / smog testing. Frequently sets alongside P0141 when the sensor heater has failed
What causes P0140 on a Chevrolet?
Open circuit in the O2 signal or ground wire (most-common). Failed Bank 1 downstream O2 sensor (dead element) (most-common). Failed sensor heater leaving the sensor below operating temperature (common). Blown O2 heater fuse (common). Corroded or disconnected downstream O2 sensor connector (common). Harness chafed or melted against the exhaust (common). Failed PCM input for the downstream sensor circuit (rare)
Is it safe to drive a Chevrolet with P0140?
In most cases a Chevrolet stays drivable for short trips with P0140 active, but it should be diagnosed and repaired promptly — this is a moderate-severity code. Ignoring it can lead to further damage or a failed emissions test. Exact tolerance depends on the model and engine.