P0137 “O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)”
What is code P0137?
Code P0137 stands for “O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2)”. This diagnostic trouble code can show up for a number of problems related to the post-catalyst oxygen sensor. Therefore, it is important to have a qualified technician diagnose the specific problem that caused the code to be stored in your vehicle’s computer.
Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.
What does code P0137 mean?
A code P0137 presents evidence to a technician that there is a problem with the oxygen sensor that is mounted in the exhaust system downstream of the catalytic converter. The ECM (Engine Control Module) has detected the problem and turned on the check engine light.
Even under the best of conditions, the internal combustion engine in your vehicle will emit harmful greenhouse gasses when it is running. These gasses are a natural byproduct of the combustion process. Because of this issue, the federal government has required for many years that auto manufacturers install a device called a catalytic converter in the exhaust system to mitigate those harmful pollutants before they can exit the tailpipe.
The catalytic converter (sometimes referred to as the “catalyst” due to the chemical reaction brought about by the components inside) contains a matrix filled with platinum or other precious metal, such as palladium or rhodium. These metallic chemical elements serve as the catalyst for various chemical reactions with the exhaust gasses that pass through. The result of these reactions is that harmful carbon monoxide, hydrocarbon, and nitrogen oxide are converted into carbon dioxide, water, and nitrogen and released into the atmosphere.
Because the function of the catalytic converter is so important, a pair of oxygen sensors (O2 sensors) are placed in the exhaust stream, one ahead of the catalytic converter and the other behind. If there is too much oxygen coming out of the catalytic converter, the oxygen sensor will put out a low voltage signal. When the ECM detects lower than normal voltage for a certain period of time from the downstream sensor, indicating a lean operating condition, it stores code P0137 and turns on the check engine light. Vehicles with “V” style engines (as in V6 or V8) might have more than one set of oxygen sensors. In those cases, this code relates to “Bank 1”, the side of the engine that contains the number 1 cylinder.
What causes code P0137?
A number of causes can trigger a code P0137. That is why an accurate diagnosis is essential. Causes of this code include:
Most likely
- Faulty oxygen sensor ($200-$500)
- Damaged or deteriorated wiring to the oxygen sensor
- Bad catalytic converter ($240-$2400)
Other possibilities
- Exhaust system leak
- Leak in the intake system
- Low fuel pressure
- Bad engine coolant temperature sensor
- Engine running lean, causing excessive oxygen in the exhaust system stream
- Malfunctioning ECM
What symptoms are associated with this code?
Common signs associated with a code P0137 include the following:
- The check engine light is on or flashing
- Reduced fuel economy due to excess fuel consumption
- Failed emissions test
- Engine runs roughly or lacks power
- Strange smell coming from the exhaust
How does a technician diagnose code P0137?
If a diagnostic scan of your vehicle indicates a code P0137, a technician will perform tests to pinpoint the problem. These tests include checking for any related trouble codes. The technician will also use the scan tool to read the live data from the oxygen sensors and check for problems with the wiring that leads to the sensors. Electrical testing of the sensor using a multimeter might also be done. The technician might even remove the oxygen sensor from the vehicle for testing. Other tests might be conducted to determine if, instead, the problem is caused by faulty engine fuel management.
How serious is this code?
In some cases, a code P0137 will not cause immediate drivability issues. However, driving your vehicle with this code means that the ECM cannot accurately monitor the efficiency of the catalytic converter. The exhaust system might also be leaking. But it also means that your engine could be running excessively lean, a condition that can lead to significant internal engine damage. While a code P0137 might not be an immediate risk, ignoring the condition can cost you thousands of dollars in damage if left unchecked for too long.
Get this checked out soon by a CarAdvise shop, where the work will be guaranteed, and one of our expert techs will review any repair orders.
Related Diagnostic Trouble Codes
P0132 “O2 Sensor Circuit High Voltage (Bank 1, Sensor 1)”
P0138 “O2 Sensor Circuit High Voltage (Bank 1, Sensor 2)”
P0158 “O2 Sensor Circuit High Voltage (Bank 2, Sensor 2)”
