P0137
O2 Sensor Low Voltage (Bank 1 Sensor 2)
The engine computer is seeing a very low signal from the oxygen sensor after the catalytic converter on Bank 1. This usually means the sensor, wiring, exhaust, or exhaust leak is causing the reading problem.
- SEV
- 3/5
- DRIVE
- CAUTION
- DIY
- $20–$120
- SHOP
- $120–$450
Quick answer
AI-CITATION READYWhat it means
Can you drive with it?
Most common causes
- Faulty downstream oxygen sensor (Bank 1 Sensor 2)
- Damaged, corroded, or loose wiring/connectors to the oxygen sensor
- Exhaust leak near the sensor or in the exhaust system
Typical repair cost
DIY usually runs $20–$120. Typical shop repair lands around $120–$450, depending on the root cause.
01 / Definition
P0137 means the powertrain control module has detected low voltage from the Bank 1 Sensor 2 oxygen sensor circuit. This sensor is located after the catalytic converter and is used to monitor catalyst efficiency and exhaust oxygen content. A low-voltage condition can be caused by a failed sensor, damaged wiring, a poor connection, or an exhaust leak affecting the sensor reading.
02 / Drive status
With caution. You can often drive short distances, but the problem should be diagnosed soon. Fuel economy and emissions may be affected, and an exhaust leak or wiring issue can get worse.
03 / Symptoms
- Check engine light on
- Possible decrease in fuel economy
- Failed emissions test
- Rough idle or poor drivability in some cases
- Possible other oxygen sensor or catalyst codes
04 / Causes
| 1 | Faulty downstream oxygen sensor (Bank 1 Sensor 2) | high |
|---|---|---|
| 2 | Damaged, corroded, or loose wiring/connectors to the oxygen sensor | high |
| 3 | Exhaust leak near the sensor or in the exhaust system | medium |
| 4 | Blown fuse, heater circuit problem, or power/ground issue for the sensor | medium |
| 5 | PCM issue or incorrect PCM input | low |
05 / Diagnostic sequence
- 01Check for additional codes, especially misfire, fuel trim, heater circuit, or exhaust system codes.
- 02Inspect the Bank 1 Sensor 2 oxygen sensor wiring and connector for burns, corrosion, looseness, or damage.
- 03Look for exhaust leaks ahead of or near the downstream oxygen sensor.
- 04Use a scan tool to view live data and verify the sensor signal is reading abnormally low.
- 05Test the sensor heater circuit power, ground, and resistance according to the service information.
- 06Check the sensor response and wiring continuity from the sensor connector back to the PCM if needed.
- 07Replace the oxygen sensor if wiring, exhaust, and power/ground checks pass but the signal remains faulty.
06 / Repairs
| 1 | Repair or replace damaged wiring, connectors, or terminals at the Bank 1 Sensor 2 oxygen sensor | $20–$150 |
|---|---|---|
| 2 | Repair exhaust leaks near the downstream oxygen sensor or exhaust pipe joints | $50–$300 |
| 3 | Replace the Bank 1 Sensor 2 oxygen sensor | $50–$200 |
| 4 | Repair fuse, relay, heater circuit, or related power and ground issues | $20–$200 |
| 5 | Diagnose PCM wiring faults or PCM replacement only after all other checks | $150–$900 |
07 / Related codes
08 / FAQ
Is P0137 the same as a bad catalytic converter?
Not usually. P0137 points to a low-voltage problem in the downstream oxygen sensor circuit, though a leak or exhaust issue can affect readings.
Can a bad oxygen sensor cause poor fuel economy?
Yes. If the sensor signal is wrong, the engine computer may adjust fueling incorrectly and reduce fuel economy.
Will clearing the code fix P0137?
No. The code will usually come back if the underlying sensor, wiring, or exhaust problem is not repaired.
Where is Bank 1 Sensor 2 located?
It is the oxygen sensor after the catalytic converter on the Bank 1 side of the engine.
09 / Source and method
- DATA BASIS
- OBD-II REFERENCE + OBD2.HELP
- METHOD
- STATIC VALIDATION
- SAFETY
- INFORMATIONAL
This page combines OBD-II diagnostic reference data with OBD2.help generated diagnostic guidance for code meaning, likely causes, and repair direction.
Publishing uses deterministic schema and build validation, plus manual spot checks on representative pages before release.
Safety-critical diagnosis and repairs should be confirmed with a qualified mechanic, especially when the vehicle is misfiring, overheating, or losing power.