P0137 on a 2022 GMC Sierra 1500
Post-Cat O2 Sensor Low Voltage (Bank 1 Downstream)
P0137 on a 2022 GMC Sierra 1500 indicates post-cat o2 sensor low voltage (bank 1 downstream). It usually stays drivable short-term but should be diagnosed promptly. The most common cause is downstream o2 signal wire shorted to ground or open (typically $80–$350). Confirm the root cause before replacing parts.
What does P0137 mean on a 2022 GMC Sierra 1500?
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.
The symptoms, causes, and diagnostic steps below describe P0137 itself, so they read the same on nearby GMC Sierra 1500 model years. Powertrain and trim details vary year to year — confirm the specifics against your own vehicle before buying parts.
Is it safe to drive a 2022 GMC Sierra 1500 with P0137?
In most cases a 2022 GMC Sierra 1500 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.
What are the symptoms of P0137 on a 2022 GMC Sierra 1500?
- 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 2022 GMC Sierra 1500?
| 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 |
Cost ranges are editorial estimates for parts and labor at an independent U.S. shop — not quotes. What you actually pay moves with your region, the shop's hourly rate, which engine you have, and how much diagnostic time the job takes. Dealer service departments typically sit above these ranges.
How to diagnose this on a 2022 GMC Sierra 1500
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Confirm you are at the right sensor before touching anything
Bank 1 Sensor 2 is downstream of the catalytic converter on the bank containing cylinder number 1. On an inline engine there is only one bank, so it is simply the sensor after the cat. On a V engine you have to establish which bank holds cylinder 1 first. Replacing the upstream sensor by mistake is the single most common wasted repair on this code.
Tools: Vehicle-specific service information, Vehicle lift or jack stands
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Read fuel trims to separate a real lean condition from a sensor fault
Check Bank 1 long-term fuel trim at idle and at 2500 RPM. Near zero means the engine is fuelling correctly and the sensor or its wiring is lying. Trim at +15 % or higher means the engine really is lean, the sensor is reporting honestly, and your job is to find the vacuum or exhaust leak — not to buy an O2 sensor.
Tools: Scan tool with live fuel trim PIDs
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Disconnect the sensor and look for bias voltage
Unplug the downstream sensor. With the key on, the scan tool PID should show the ECM's bias voltage, usually around 0.4–0.5 V. If the reading stays pinned at zero with the sensor disconnected, the signal wire is shorted to ground somewhere between the connector and the PCM, and a new sensor will not change a thing.
Tools: Scan tool, Multimeter
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Inspect the harness and connector under the vehicle
The downstream sensor and its harness live under the car in road spray and salt. Trace the wiring from the sensor body back to the chassis connector looking for melted insulation where it has touched the exhaust, chafing against the underbody, and rodent damage. Open the connector and check for water and green corrosion.
Tools: Flashlight, Inspection mirror, Electrical contact cleaner
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Find exhaust leaks between the catalyst and the sensor
A pinhole or a leaking flange gasket ahead of the downstream sensor lets fresh air into the exhaust stream, and the sensor correctly reports the oxygen it sees — as a permanently low voltage. Listen along the pipe with the engine cold, or use a smoke machine on the exhaust to make small leaks visible.
Tools: Mechanic's stethoscope, Smoke machine (optional), Flashlight
NHTSA complaints & recalls for the 2022 GMC Sierra 1500
Owner-reported safety complaints and official recalls filed with the U.S. National Highway Traffic Safety Administration for the 2022 GMC Sierra 1500. Use these to gauge how common a problem is on your specific vehicle before you start chasing GMC Sierra 1500 diagnostics.
- ENGINE 207
- POWER TRAIN 92
- STRUCTURE 90
- ELECTRICAL SYSTEM 75
- UNKNOWN OR OTHER 70
6 active recalls
- EXTERIOR LIGHTING:BRAKE LIGHTS Jun 2022
General Motors (GM) has decided that certain 2022 model year Chevrolet Silverado, and GMC Sierra vehicles equipped with an accessory sport bar. The accessory sport bar contains a high-mounted brake light that may not function. In addition, it may block the vehicle's existing hi…
NHTSA campaign 22V463000 - EXTERIOR LIGHTING:LIGHTING CONTROL MODULE:SOFTWARE Dec 2022
General Motors, LLC (GM) is recalling certain 2020-2023 Cadillac CT4 and CT5; 2021-2023 Buick Envision; and 2022-2023 Cadillac Escalade and Escalade ESV, Chevrolet Silverado 1500, Suburban, Tahoe, GMC Sierra 1500, Yukon, and Yukon XL vehicles. The daytime running lights (DRLs) m…
NHTSA campaign 22V903000 - POWER TRAIN:AUTOMATIC TRANSMISSION:CONTROL MODULE:SOFTWARE Oct 2024
General Motors, LLC (GM) is recalling certain 2020-2022 Chevrolet Silverado 1500, 2500, 3500, GMC Sierra 1500, 2500, 3500, 2021 Cadillac Escalade, Escalade ESV, Chevrolet Tahoe, Suburban, GMC Yukon, and Yukon XL vehicles equipped with diesel engines. The transmission control val…
NHTSA campaign 24V797000 - STRUCTURE:BODY:BUMPERS:ACTIVE SHUTTERS/GRILL Feb 2025
General Motors, LLC (GM) is recalling certain 2022 GMC Sierra 1500 vehicles equipped with chrome front grille deflectors. The attachments that hold the front grille deflectors in place may fracture, resulting in grille detachment.…
NHTSA campaign 25V060000
How do I fix P0137 on a 2022 GMC Sierra 1500?
- Replace the Bank 1 downstream O2 sensor with an OEM part
- Repair the shorted-to-ground or open O2 signal wire
- Repair exhaust leaks between the catalyst and the downstream sensor
- Clean or replace the corroded downstream sensor connector
- Repair vacuum leaks if fuel trims confirm a genuine lean condition
Bank 1 Sensor 2 means the sensor after the catalytic converter
This is worth being pedantic about, because getting it wrong sends you to the wrong part of the exhaust:
- Sensor 1 — upstream, before the catalyst, usually threaded into the exhaust manifold or the downpipe. This is the sensor that drives fuel control.
- Sensor 2 — downstream, after the catalyst, underneath the vehicle. This is the sensor that monitors whether the catalyst is still working.
P0137 is a Sensor 2 code. If you are reaching down past the manifold, you are at the wrong sensor.
Is the sensor lying, or is the engine actually lean?
Fuel trim answers this in about thirty seconds, and it decides the entire repair:
- Trim near zero, P0137 alone → the engine is fuelling correctly. The sensor or its circuit is at fault. Test the wiring, then replace the sensor.
- Trim high positive, often with P0171 → the engine really is running lean and the downstream sensor is honestly reporting it. Replacing the sensor fixes nothing. Go find the vacuum leak, the exhaust leak, or the fuel delivery problem.
Why the car drives fine with P0137
The downstream sensor’s primary job is monitoring catalyst efficiency, not controlling fuel delivery — that is the upstream sensor’s role. It contributes only a slow secondary correction to fuel trim. So a failed downstream sensor almost always shows up as a light on the dash and a failed emissions test, not as a car that runs badly. That makes P0137 non-urgent from a drivability standpoint, but it does not make it optional: the catalyst monitor cannot complete while it is set, and most emissions programmes treat an incomplete monitor as a failure.
Buy the sensor once
Aftermarket oxygen sensors at a fraction of OEM pricing have a real track record of setting the same code again within months. The downstream sensor is a comparison device rather than a precision measurement device, so it is slightly more forgiving than the upstream one — but not forgiving enough to be worth the second job. Bosch, Denso, or NTK in the exact part number listed for your year, make, model, engine, and emissions package.
P0137 on a 2022 GMC Sierra 1500: frequently asked questions
What does diagnostic trouble code P0137 mean on a 2022 GMC Sierra 1500?
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.
What are the symptoms of P0137 on a 2022 GMC Sierra 1500?
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 2022 GMC Sierra 1500?
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 2022 GMC Sierra 1500 with P0137?
In most cases a 2022 GMC Sierra 1500 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.