CAR OBD CODES

P0166 OBD Code Definition:
P0166 O2 Sensor Circuit No Activity Detected Bank 2 Sensor 3
P0166 OBD Code Description:

OBD2 Code P0166 Definition:
The rear heated oxygen sensor (or sensor 3 for some vehicles), after three way catalyst (manifold), monitors the oxygen level in the exhaust gas on each bank. Even if switching characteristics of the heated oxygen sensor 1 are shifted, the air-fuel ratio is controlled to stoichiometric, by the signal from the heated oxygen sensor 3. This sensor is made of ceramic zirconia. The zirconia generates voltage from approximately 1V in richer conditions to 0V in leaner conditions. Under normal conditions the heated oxygen sensor 3 is not used for engine control operation. Symptoms

Possible sumptoms of P0166
– Engine Light ON (or Service Engine Soon Warning Light) – High Fuel Consumption – Excessive Smoke from Exhaust Possible Causes

Possible causes of P0166
– Harness or connectors (The sensor circuit is open or shorted) – Rear heated oxygen sensor (Bank 2) may be faulty The Error code is generally activated on detection of the following conditions: Current amperage in the rear heated oxygen sensor heater circuit is out of the normal range. (An improper voltage drop signal is sent to ECM through the rear heated oxygen sensor heater
Note: The information on the P0166 error code is purely informative, if you need more useful information, please consult your technician.