Powertrain, generic (extended)

P2BDE Motor Electronics Coolant Temperature Sensor C Circuit Low

Check engine lightOn
EmissionsRelevant
Drive cycleNot required
Limp modePossible

P2BDE reports that the voltage from coolant temperature sensor C has dropped below its lower limit. Low describes the voltage: for the usual NTC sensor it corresponds to a reading far hotter than the coolant can be, and the cause is mostly a grounded signal wire, a crushed pigtail or a sensor that has shorted internally. No manufacturer documents P2BDE publicly. GM's electronics coolant sensor in the Volt and ELR, monitored as P0CF0, shows typical limits: below 2 % of the 5 V reference (0.1 V) in the 2011 tables and below 4 % (0.2 V) in the 2016 Volt table, 16 of 20 samples at 250 ms, Type B. The open or high case is P2BDF, while the matching low fault of sensor B is P2BDA. Drive power may be limited as a precaution.

Likely causes

Sensor C signal wire shorted to ground or to the sensor ground
Sensor C shorted internally
Crushed or melted sensor pigtail near hot components
Faulty analog input in the evaluating module

Symptoms

  • Hybrid warning or check engine light
  • Very high electronics coolant temperature shown in live data on a cold vehicle
  • Fan running at full speed shortly after start

Repair estimate

DifficultyMediumWorkshop job
Parts and labour€60–500
Time0.5–2.5 h

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

Parts involved

motor electronics coolant temp sensor cwiring harnesshybrid control module

Related codes

P2BDCP2BDDP2BDFP2BDAP0CF0

References: gsi.ext.gm.com, gsi.ext.gm.com, law.cornell.edu.