Code PO 137....
Thread Starter
Racer
Joined: Oct 2005
Posts: 342
Likes: 0
From: Anderson SC
Code PO 137....
I did a search and didnt come up with what I needed to know, so...
My check engine light came on the other day. I had it scanned, and the code read PO 137, low voltage, O2 sensor, bank 1, sensor 2. According to auto zone, bank 1 sensor 2 is the sensor after the cat on the drivers side.
Well, I bought a new sensor, put it on , cleared the code error, and thought everything was fine. 10 miles or so down the rode, the CE light came on again. I went back to auto zone, had it scanned , same code, PO 137, low voltage etc...
I really would like to fix this myself without having to take it to a dealership to have warranty work done, so does anyone know what the problem might be?
Thanks in advance.
My check engine light came on the other day. I had it scanned, and the code read PO 137, low voltage, O2 sensor, bank 1, sensor 2. According to auto zone, bank 1 sensor 2 is the sensor after the cat on the drivers side.
Well, I bought a new sensor, put it on , cleared the code error, and thought everything was fine. 10 miles or so down the rode, the CE light came on again. I went back to auto zone, had it scanned , same code, PO 137, low voltage etc...
I really would like to fix this myself without having to take it to a dealership to have warranty work done, so does anyone know what the problem might be?
Thanks in advance.
Team Owner
Joined: Sep 2001
Posts: 23,283
Likes: 905
From: Lake Elsinore, CA
This'll get you started - part of the diagnostics out of the manual.
DTC P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
Circuit Description
The PCM supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.
The PCM monitors the HO2S voltage for being fixed below a predetermined voltage. If the PCM detects the voltage is below a predetermined voltage, a DTC sets.
Conditions for Running the DTC
Criteria 1
DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0200, P0335, P0336, P0351-P0358, P1120, P1220, P1221, P1258 are not set.
The ignition voltage is greater than 9.0 volts.
The fuel system is operating in Closed Loop.
The AIR and the Catalyst diagnostics are not active.
The TP angle is between 2% and 70%.
OR
Criteria 2
DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0200, P0335, P0336, P0351-P0358, P1120, P1220, P1221, P1258 are not set.
The ignition voltage is greater than 9.0 volts.
The AIR and the Catalyst diagnostics are not active.
The Power Enrichment mode is enabled for greater than 1.0 second.
Conditions for Setting the DTC
Criteria 1
The HO2S signal voltage remains below 80 mV.
The Criteria 1 conditions are present for 80 seconds.
OR
Criteria 2
The HO2S signal voltage remains below 420 mV.
The Criteria 2 conditions are present for 10.0 seconds during the Power Enrichment mode.
Action Taken When the DTC Sets
The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.
The PCM sets this DTC when the vehicle runs out of fuel.
Heated Oxygen Sensor (HO2S) wire: Sensor pigtail may be in contact with the exhaust manifold or the exhaust system.
An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Wiring Repairs in Wiring Systems.
Inspect for an intermittent ground in the signal wire between the connector and the sensor.
Lean injector(s): Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool .
Fuel contamination: Water near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can set a DTC. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Fuel pressure: System will be lean if fuel pressure is low. Refer to Fuel System Diagnosis .
Exhaust leaks: An exhaust leak near the HO2S can cause a lean condition. Refer to Inspection Procedure in Engine Exhaust.
Vacuum or crankcase leaks can cause a lean condition.
If the above are OK, the HO2S may be at fault.
Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This isolates when the DTC failed.
For an intermittent condition, refer to Symptoms.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
If the HO2S voltage is fixed well below 200 mV, this indicates a short to battery ground or chassis ground. If the voltage is fixed near or above 200 mV, this indicates a short to a PCM ground. When the HO2S voltage is fixed near 200 mV, indicates the DTC set when the fuel system was in a Power Enrichment mode of operation. This DTC sets if the HO2S voltage is less than 420 mV during a Power Enrichment mode of operation.
The engine must be at the normal operating temperature before performing this test.
Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you can not duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that the PCM recorded. This isolates when the DTC failed.
A sensor that is disconnected should indicate a bias voltage. If the voltage is low inspect the signal circuit for a short to ground.
Lower the exhaust system to gain sufficient access to the HO2S and/or the HO2S connector if necessary.
Disconnecting the PCM allows using a DMM in order in order to test continuity of the circuits. This aids in locating an open or shorted circuit.
DTC P0137 HO2S Circuit Low Voltage Bank 1 Sensor 2
Circuit Description
The PCM supplies a voltage of about 450 mV between the HO2S high and low signal circuits. The oxygen sensor varies the voltage over a range from about 1,000 mV when the exhaust is rich, down through about 10 mV when the exhaust is lean.
The PCM monitors and stores the heated oxygen sensor (HO2S) voltage information. The PCM evaluates the HO2S voltage samples in order to determine the amount of time the HO2S voltage was out of range. The PCM compares the stored HO2S voltage samples taken within each sample period and determines if majority of the samples are out of the operating range.
The PCM monitors the HO2S voltage for being fixed below a predetermined voltage. If the PCM detects the voltage is below a predetermined voltage, a DTC sets.
Conditions for Running the DTC
Criteria 1
DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0200, P0335, P0336, P0351-P0358, P1120, P1220, P1221, P1258 are not set.
The ignition voltage is greater than 9.0 volts.
The fuel system is operating in Closed Loop.
The AIR and the Catalyst diagnostics are not active.
The TP angle is between 2% and 70%.
OR
Criteria 2
DTCs P0101, P0102, P0103, P0112, P0113, P0117, P0118, P0125, P0200, P0335, P0336, P0351-P0358, P1120, P1220, P1221, P1258 are not set.
The ignition voltage is greater than 9.0 volts.
The AIR and the Catalyst diagnostics are not active.
The Power Enrichment mode is enabled for greater than 1.0 second.
Conditions for Setting the DTC
Criteria 1
The HO2S signal voltage remains below 80 mV.
The Criteria 1 conditions are present for 80 seconds.
OR
Criteria 2
The HO2S signal voltage remains below 420 mV.
The Criteria 2 conditions are present for 10.0 seconds during the Power Enrichment mode.
Action Taken When the DTC Sets
The PCM illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The PCM records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the PCM stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the PCM records the operating conditions at the time of the failure. The PCM writes the conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The PCM turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A last test failed, or current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Use a scan tool in order to clear the MIL and the DTC.
Diagnostic Aids
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
For any test that requires probing the PCM or a component harness connector, use the Connector Test Adapter Kit J 35616-A . Using this kit prevents damage to the harness/component terminals. Refer to Using Connector Test Adapters in Wiring Systems.
The PCM sets this DTC when the vehicle runs out of fuel.
Heated Oxygen Sensor (HO2S) wire: Sensor pigtail may be in contact with the exhaust manifold or the exhaust system.
An oxygen supply inside the HO2S is necessary for proper operation. The HO2S wires provides the supply of oxygen. Inspect the HO2S wires and connections for breaks or contamination. Refer to Wiring Repairs in Wiring Systems.
Inspect for an intermittent ground in the signal wire between the connector and the sensor.
Lean injector(s): Perform the Injector Balance Test. Refer to Fuel Injector Balance Test with Tech 2 or Fuel Injector Balance Test with Special Tool .
Fuel contamination: Water near the in-tank fuel pump inlet can be delivered to the injectors. The water causes a lean exhaust and can set a DTC. Refer to Alcohol/Contaminants-in-Fuel Diagnosis .
Fuel pressure: System will be lean if fuel pressure is low. Refer to Fuel System Diagnosis .
Exhaust leaks: An exhaust leak near the HO2S can cause a lean condition. Refer to Inspection Procedure in Engine Exhaust.
Vacuum or crankcase leaks can cause a lean condition.
If the above are OK, the HO2S may be at fault.
Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you cannot duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also help determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that you observed. This isolates when the DTC failed.
For an intermittent condition, refer to Symptoms.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
If the HO2S voltage is fixed well below 200 mV, this indicates a short to battery ground or chassis ground. If the voltage is fixed near or above 200 mV, this indicates a short to a PCM ground. When the HO2S voltage is fixed near 200 mV, indicates the DTC set when the fuel system was in a Power Enrichment mode of operation. This DTC sets if the HO2S voltage is less than 420 mV during a Power Enrichment mode of operation.
The engine must be at the normal operating temperature before performing this test.
Using the Freeze Frame and/or Failure Records data may aid in locating an intermittent condition. If you can not duplicate the DTC, the information included in the Freeze Frame and/or Failure Records data can help determine how many miles since the DTC set. The Fail Counter and Pass Counter can also be used to determine how many ignition cycles the diagnostic reported a pass and/or a fail. Operate the vehicle within the same freeze frame conditions (RPM, load, vehicle speed, temperature etc.) that the PCM recorded. This isolates when the DTC failed.
A sensor that is disconnected should indicate a bias voltage. If the voltage is low inspect the signal circuit for a short to ground.
Lower the exhaust system to gain sufficient access to the HO2S and/or the HO2S connector if necessary.
Disconnecting the PCM allows using a DMM in order in order to test continuity of the circuits. This aids in locating an open or shorted circuit.
Le Mans Master
Joined: Aug 2003
Posts: 9,298
Likes: 4
From: American Canyon Lethal Injection
Originally Posted by deec73
I did a search and didnt come up with what I needed to know, so...
My check engine light came on the other day. I had it scanned, and the code read PO 137, low voltage, O2 sensor, bank 1, sensor 2. According to auto zone, bank 1 sensor 2 is the sensor after the cat on the drivers side.
Well, I bought a new sensor, put it on , cleared the code error, and thought everything was fine. 10 miles or so down the rode, the CE light came on again. I went back to auto zone, had it scanned , same code, PO 137, low voltage etc...
I really would like to fix this myself without having to take it to a dealership to have warranty work done, so does anyone know what the problem might be?
Thanks in advance.
My check engine light came on the other day. I had it scanned, and the code read PO 137, low voltage, O2 sensor, bank 1, sensor 2. According to auto zone, bank 1 sensor 2 is the sensor after the cat on the drivers side.
Well, I bought a new sensor, put it on , cleared the code error, and thought everything was fine. 10 miles or so down the rode, the CE light came on again. I went back to auto zone, had it scanned , same code, PO 137, low voltage etc...
I really would like to fix this myself without having to take it to a dealership to have warranty work done, so does anyone know what the problem might be?
Thanks in advance.
Good luck
SC5
Thread Starter
Racer
Joined: Oct 2005
Posts: 342
Likes: 0
From: Anderson SC
Just a question, why do go to Auto Zone to scan for codes rather than just call them up on your DIC?
Just a matter of conveinence I guess, lol.
Thanks for the tips above guys. It seems a small exhaust leak was causing the CE light to come on. Time will tell.
