DTC P0137 Or DTC P0138: Condition

DTC P0137 is set when Heated Oxygen Sensor (HO2S) No. 2 minimum voltage is higher than .25 volts while fuel cut for 4 seconds and then engine is at idle for 6 seconds. DTC P0138 is set when maximum HO2S No. 2 output voltage is higher than 2 volts for 20 seconds, or maximum HO2S No. 2 voltage is less than .35 volt for 8 minutes. MIL is illuminated when Engine Control Module (ECM) detects malfunction during 2 consecutive drive cycles. Possible causes are:

• Open or short to ground in circuit between HO2S No. 2 and ECM.
• HO2S No. 2 malfunction.
• Fuel system malfunction.
• ECM malfunction.
• Fuel system malfunction.
• Low fuel level.