DTC
Description
Possible Cause
Action
W iring between
upstream O2 sensor
and ECM
Fuel injector flow
partially blocked
Catalyst efficiency
decrease
P0051 HO2S Heater Control
Circuit Low (Bank 2,
Sensor 1)
Concern with
upstream O2 sensor
heater
W iring fault
between upstream
O2 sensor and ECM
W iring fault
between Upstream
O2 sensor and Front
Power Distribution
Box
Check power supply to HO2S heater element connector pin with the ignition on. If
the voltage is less than 10.5 volts check the front power distribution box fuses.
Check the wiring circuit from the front power distribution box to the HO2S sensor
connector for open circuits or shorts to ground. Repair any wiring faults using
approved methods and materials, replace any blown fuses and clear the DTC.
retest the system for correct operation. Check wiring circuit between the HO2S
sensor connector and the engine control module.
P0052 HO2S Heater Control
Circuit High (Bank 2,
Sensor 1)
Concern with
upstream O2 sensor
heater
W iring fault
between upstream
O2 sensor and ECM
Check power supply to HO2S heater element connector pin with the ignition on. If
the voltage is less than 10.5 volts check the front power distribution box fuses.
Check the wiring circuit from the front power distribution box to the HO2S sensor
connector for open circuits or shorts to ground. Repair any wiring faults using
approved methods and materials, replace any blown fuses and clear the DTC.
retest the system for correct operation.
P0137 O2 Circuit Low Voltage
(Bank 1, Sensor 2)
Concern with
downstream O2
sensor
W iring between
downstream O2
sensor and ECM
Check oxygen sensor wiring harness for signs of damage to the insulation. Check
the signal and screen circuits for open circuits, and shorts to ground. Check
heater circuit power circuit is supplied with power and the control line is not open
circuit. Check sensor for evidence of fouling
P0138 O2 Circuit High Voltage
(Bank 1, Sensor 2)
Concern with
downstream O2
sensor heater
W iring fault
between
downstream O2
sensor and ECM
W iring fault
between
downstream O2
sensor and Front
Power Distribution
Box
Check oxygen sensor wiring harness for signs of damage to the insulation. Check
the signal and screen circuits for shorts to power.
P0140 O2 Circuit No Activity
Detected (Bank 1,
Sensor 2)
Power supply to
oxygen sensor
heater not present
W iring harness fault
Oxygen sensor
faulty
Check power distribution box fuses to ensure the heater element of the oxygen
sensor is powered. Check oxygen sensor heating element control line is not open
circuit or has a high resistance. Check sensor signal lines for open circuits and
shorts to ground. Repair wiring fault using approved methods and materials.
Check oxygen sensor for contamination or masked sensing tip. Replace the
sensor if suspect. Clear DTC, retest the system to confirm correct operation.
P0037 HO2S Heater Control
Circuit Low (Bank 1,
Sensor 2)
Concern with
downstream O2
sensor heater
W iring fault
between
downstream O2
sensor and ECM
W iring fault
between
downstream O2
sensor and Front
Power Distribution
Box
Check power supply to HO2S heater element connector pin with the ignition on. If
the voltage is less than 10.5 volts check the front power distribution box fuses.
Check the wiring circuit from the front power distribution box to the HO2S sensor
connector for open circuits or shorts to ground. Repair any wiring faults using
approved methods and materials, replace any blown fuses and clear the DTC.
retest the system for correct operation.
P0038 HO2S Heater Control
Circuit High (Bank 1,
Sensor 2)
Concern with
downstream O2
sensor heater
W iring fault
between
downstream O2
sensor and ECM
Check engine wiring harness for signs of damage. Check HO2S heater control
circuit for short to power. Check HO2S for internal short circuit. Repair wiring
using appropriate methods and materials, clear DTC and retest system for correct
operation. Replace HO2S if suspect. Clear DTC and retest systems to confirm
correct operation.
P0157 O2 Circuit Low Voltage
(Bank 2, Sensor 2)
Concern with
downstream O2
sensor
W iring fault
between
downstream O2
sensor and ECM
Check oxygen sensor wiring harness for signs of damage to the insulation. Check
the signal and screen circuits for open circuits, and shorts to ground. Check
heater circuit power circuit is supplied with power and the control line is not open
circuit. Check sensor for evidence of fouling
P0158 O2 Circuit High Voltage
(Bank 2, Sensor 2)
Concern with
downstream O2
sensor
W iring fault
between
downstream O2
sensor and ECM
Check oxygen sensor wiring harness for signs of damage to the insulation. Check
the signal and screen circuits for shorts to power.