Oxygen Sensor Training Guide

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6.0 COMMON OBDII CODES

When an O2 sensor failure occurs, a DTC or diagnostic trouble code is recorded in the ECU and a check engine light appears on the vehicle’s dash. The DTC must be retrieved using a scanning tool. There are generic or standard OBDII codes along with enhanced or OEM specific codes. Below is a list of the more common OBDII codes, along with the possible cause or causes of the code.

 

Code Description Location Possible Causes
P0150 O2 Sensor Circuit Malfunction Bank 2 Sensor 1 Broken sensor element. Sensor disconnected. Shorted wiring. Catastrophic failure of sensor due to thermal shock.
P0151 O2 Sensor Circuit Low Voltage Bank 2 Sensor 1 Short in wiring between sensor ground and signal wire. Silicone or ethylene glycol poisoning of the air reference electrode.
P0152 O2 Sensor Circuit High Voltage Bank 2 Sensor 1 Short in wiring between heater circuit and signal wire. Sensor immersed in water. Silicone or ethylene glycol poisoning of the sensing electrode.
P0153 O2 Sensor Circuit Slow Response Bank 2 Sensor 1 Sensor electrode protective coated with carbon. Silicone poisoning. Ethylene glycol poisoning. Failed sensor heater. Heater circuit fuse.
P0154 O2 Sensor Circuit No Activity Detected Bank 2 Sensor 1 Short in wiring between sensor ground and signal wire. Silicone or ethylene glycol poisoning of the air reference electrode.
P0155 O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 1 Sensor heater shorted or open. Replacement sensor installed with incorrect heater current values. Open or shorted electrical connections. Heater circuit fuse.
P0156 O2 Sensor Circuit Sensor Malfunction Bank 2 Sensor 2 Broken sensor element. Sensor disconnected. Shorted wiring. Catastrophic failure of sensor due to thermal shock.
P0157 O2 Sensor Circuit Low Voltage Bank 2 Sensor 2 Short in wiring between sensor ground and signal wire. Silicone or ethylene glycol poisoning of the air reference electrode.
P0158 O2 Sensor Circuit High Voltage Bank 2 Sensor 2 Short in wiring between heater circuit and signal wire. Sensor immersed in water. Silicone or ethylene glycol poisoning of the sensing electrode.
P0159 O2 Sensor Circuit Slow Response Bank 2 Sensor 2 Sensor electrode protective coated with carbon. Silicone poisoning. Ethylene glycol poisoning. Failed sensor heater. Heater circuit fuse.
P0160 O2 Sensor Circuit No Activity Detected Bank 2 Sensor 2 Short in wiring between sensor ground and signal wire. Silicone or ethylene glycol poisoning of the air reference electrode.
P0161 O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 2 Sensor heater shorted or open. Replacement sensor installed with incorrect heater current values. Open or shorted electrical connections. Heater circuit fuse.
P0162 O2 Sensor Circuit Malfunction Bank 2 Sensor 3 Broken sensor element. Sensor disconnected. Shorted wiring. Catastrophic failure of sensor due to thermal shock.
P0163 O2 Sensor Circuit Low Voltage Bank 2 Sensor 3 Short in wiring between sensor ground and signal wire. Silicone or ethylene glycol poisoning of the air reference electrode.
P0164 O2 Sensor Circuit High Voltage Bank 2 Sensor 3 Short in wiring between heater circuit and signal wire. Sensor immersed in water. Silicone or ethylene glycol poisoning of the sensing electrode.
P0165 O2 Sensor Circuit Slow Response Bank 2 Sensor 3 Sensor electrode protective coated with carbon. Silicone poisoning. Ethylene glycol poisoning. Failed sensor heater. Heater circuit fuse.
P0166 O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3 Short in wiring between sensor ground and signal wire. Silicone or ethylene glycol poisoning of the air reference electrode.
P0167 O2 Sensor Heater Circuit Malfunction Bank 2 Sensor 3 Sensor heater shorted or open. Replacement sensor installed with incorrect heater current values. Open or shorted electrical connections. Heater circuit fuse.
P0170 Fuel Trim Malfunction Bank 1 Vacuum Leak. Gas in engine oil. Air leaks. Bad O2 Sensor.
P0171 System Too Lean Bank 1 Leaking exhaust gasket or vacuum lines. Defective fuel injector(s). Damaged fuel pump. Clogged fuel filter.
P0172 System Too Rich Bank 1 Vacuum leak. Fuel pressure or delivery problem. Faulty MAF sensor.
P0173 Fuel Trim Malfunction Bank 2 Vacuum Leak. Gas in engine oil. Air leaks. Bad O2 Sensor.
P0174 System Too Lean Bank 2 Leaking exhaust gasket or vacuum lines. Defective fuel injector(s). Damaged fuel pump. Clogged fuel filter.
P0175 System Too Rich Bank 2 Vacuum Leak. Gas in engine oil. Air leaks. Bad O2 Sensor.

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