P105D Possible Causes
- Faulty O2 sensor heater, Bank 2 Sensor 2
- O2 Sensor Heater Bank 2 Sensor 2 circuit open or shorted
- Poor electrical connection in Bank 2 Sensor 2 O2 sensor heater circuit
- Faulty Engine Control Module (ECM)
How is P105D Code Repaired?
Start by checking the “Possible Causes” listed above. Visually inspect the wiring harness and associated connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Possible Symptoms
Illuminated check engine light (or service engine soon warning light)
P105D Meaning
To achieve a high purification rate of carbon monoxide (CO), hydrocarbon (HC), and nitrogen oxide (NOx) components in the exhaust gases, a TWC (three-way catalytic converter) is used. For more efficient use of the TWC, the air-fuel ratio must be precisely controlled so that it is always close to the stoichiometric air-fuel level. To help the ECM provide precise air-fuel ratio control, a heated oxygen sensor is used.
The heated oxygen sensor is located behind the TWC and detects the oxygen concentration in the exhaust gases. Since the sensor is integrated with a heater that heats the sensing portion, it is possible to detect the oxygen concentration even when the intake air volume is low (exhaust gas temperature is low).
When the air-fuel ratio becomes lean, the oxygen concentration in the exhaust gases is high. The heated oxygen sensor informs the ECM that the post-TWC air-fuel ratio is lean (low voltage, i.e., less than 0.45 V).
Conversely, when the air-fuel ratio is richer than the stoichiometric air-fuel level, the oxygen concentration in the exhaust gases is low. The heated oxygen sensor informs the ECM that the post-TWC air-fuel ratio is rich (high voltage, i.e., greater than 0.45 V). The heated oxygen sensor has the property of drastically changing its output voltage when the air-fuel ratio is near the stoichiometric level.
The ECM uses the additional information from the heated oxygen sensor to determine whether the air-fuel ratio after the TWC is rich or lean, and adjusts the fuel injection duration accordingly. Thus, if the heated oxygen sensor does not function properly due to internal malfunctions, the ECM is unable to compensate for deviations in the primary air-fuel ratio control.