P0137 on Honda vehicles
Post-Cat O2 Sensor Low Voltage (Bank 1 Downstream) — what it means on a Honda, whether it's safe to drive, and the fixes by model and year.
P0137 on a Honda means post-cat o2 sensor low voltage (bank 1 downstream). Most vehicles stay drivable short-term, but diagnose it promptly. The most common cause is downstream o2 signal wire shorted to ground or open (typically $80–$350). Pick your Honda model below for its known failure patterns, recalls, and TSBs.
What does P0137 mean on a Honda?
P0137 is set when the Bank 1 downstream oxygen sensor reports a voltage below the calibrated minimum — typically under about 0.1 V — for an extended period. Bank 1 is the cylinder bank containing cylinder number 1. Sensor 2 is the sensor AFTER the catalytic converter, not the one threaded into the exhaust manifold. A healthy downstream sensor on a warm engine holds a relatively steady 0.6–0.8 V because the catalyst smooths out the rich / lean swings coming from the engine, so a reading pinned low means an open or shorted-to-ground signal circuit, a failed sensor, or fresh air getting into the exhaust ahead of the sensor.
P0137 is a standardized OBD-II code, so its definition is the same on every Honda. What differs by model and engine is which cause is most likely — pick your Honda model below for a diagnosis tuned to its known failure patterns, recalls, and TSBs.
Is it safe to drive a Honda with P0137?
In most cases a Honda stays drivable for short trips with P0137 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 P0137 on a Honda?
| Cause | Likelihood | Estimated repair (USD) |
|---|---|---|
| Downstream O2 signal wire shorted to ground or open | Most common | $80–$350 |
| Failed Bank 1 downstream O2 sensor (stuck low) | Most common | $150–$450 |
| Exhaust leak ahead of the downstream sensor drawing in fresh air | Common | $100–$500 |
| Corroded downstream O2 sensor connector | Common | $30–$200 |
| Damaged sensor pigtail from a previous exhaust or suspension repair | Occasional | $80–$300 |
| Genuine lean condition from a vacuum leak reaching the catalyst — Here the sensor is telling the truth — fix the lean condition, not the sensor. | Occasional | $80–$600 |
| Failed PCM input for the downstream sensor circuit | Rare | $400–$1,500 |
Repair costs are typical US ranges and vary by Honda 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.
P0137 by Honda model
Select your Honda model and year for a P0137 diagnosis tuned to that vehicle's failure patterns, recalls, and TSBs.
Honda CR-V
2,324 NHTSA owner complaints · 13 recalls on record across the years covered below.
Honda Civic
1,894 NHTSA owner complaints · 13 recalls on record across the years covered below.
Honda Accord
1,078 NHTSA owner complaints · 15 recalls on record across the years covered below.
Honda Pilot
1,176 NHTSA owner complaints · 16 recalls on record across the years covered below.
Honda HR-V
191 NHTSA owner complaints · 3 recalls on record across the years covered below.
Honda Odyssey
402 NHTSA owner complaints · 16 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 P0137.
P0137 on other makes
Other codes on Honda vehicles
P0137 on a Honda: frequently asked questions
What does diagnostic trouble code P0137 mean on a Honda?
P0137 is set when the Bank 1 downstream oxygen sensor reports a voltage below the calibrated minimum — typically under about 0.1 V — for an extended period. Bank 1 is the cylinder bank containing cylinder number 1. Sensor 2 is the sensor AFTER the catalytic converter, not the one threaded into the exhaust manifold. A healthy downstream sensor on a warm engine holds a relatively steady 0.6–0.8 V because the catalyst smooths out the rich / lean swings coming from the engine, so a reading pinned low means an open or shorted-to-ground signal circuit, a failed sensor, or fresh air getting into the exhaust ahead of the sensor. P0137 is a standardized OBD-II code, so the definition is the same on every Honda — which cause is most likely varies by model and engine.
What are the symptoms of P0137 on a Honda?
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. Sometimes accompanied by P0171 if a genuine lean condition is present
What causes P0137 on a Honda?
Downstream O2 signal wire shorted to ground or open (most-common). Failed Bank 1 downstream O2 sensor (stuck low) (most-common). Exhaust leak ahead of the downstream sensor drawing in fresh air (common). Corroded downstream O2 sensor connector (common). Damaged sensor pigtail from a previous exhaust or suspension repair (occasional). Genuine lean condition from a vacuum leak reaching the catalyst (occasional). Failed PCM input for the downstream sensor circuit (rare)
Is it safe to drive a Honda with P0137?
In most cases a Honda stays drivable for short trips with P0137 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.