P01BB Engine Oil Temperature Sensor B Circuit Low

The engine oil temperature sensor B is an NTC thermistor fed with 5 V through a resistor: the hotter the oil, the lower the signal voltage. The engine module uses the oil temperature for variable cam timing (Ford disables it with cold oil or a sensor fault), engine protection and the oil life monitor; many engines have no such sensor and use a calculated oil temperature instead. Sensor B is a second oil temperature sensor whose position is defined by the manufacturer. P01BB means the signal of sensor B is below its lower limit – the NTC would report very hot oil; typically a signal wire shorted to ground or an internally shorted sensor. Thresholds are presumably similar to sensor A (Ford about 0.16–0.20 V, GM below 25 Ω) but are not documented for B. No manufacturer document using the B-sensor codes was found, so it is unclear who fits a sensor B; the description follows sensor A and CARB's circuit monitoring requirement.

Likely causes

Symptoms

• Check engine light on (depending on manufacturer)
• Oil temperature warning or maximum reading possible
• Fan possibly running constantly

Repair estimate

Typical range across vehicles; the real cost depends on what the testing finds.

Parts involved

Related codes

References: law.cornell.edu, fordservicecontent.com, en.wikipedia.org.