Faulty battery charger coupler temperature sensor; Short to ground in the sensor wiring harness; Corroded or damaged electrical connector at the coupler; Moisture intrusion into the sensor or connector; Failed control module or internal circuit fault; Physical damage to the charge coupler assembly

DTC codes / P2Exx · Hybrid propulsion / P2E51

P2E51Battery Charger Coupler Temperature Sensor D Circuit Low

Q: What does code P2E51 mean?

Battery Charger Coupler Temperature Sensor D Circuit Low. P2E51 indicates that the battery charger coupler temperature sensor, specifically its D circuit, is reporting a low signal to the vehicle's control module. The computer detects this when the sensor's output voltage falls below the expected range, which typically means the circuit is shorted to ground or the sensor has failed.

P2E51 indicates that the battery charger coupler temperature sensor, specifically its D circuit, is reporting a low signal to the vehicle's control module. The computer detects this when the sensor's output voltage falls below the expected range, which typically means the circuit is shorted to ground or the sensor has failed.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaHybrid propulsion

Symptoms you may notice

Illumination of the check engine light or service vehicle soon message
Often no symptoms besides the warning light
Reduced or disabled battery charging in plug-in hybrid or electric vehicles
Inability to initiate or complete a charging session
Overheating of the charge coupler or connector during charging
Intermittent charging interruptions or error messages on the dashboard

Common causes, most likely first

Faulty battery charger coupler temperature sensor
Short to ground in the sensor wiring harness
Corroded or damaged electrical connector at the coupler
Moisture intrusion into the sensor or connector
Failed control module or internal circuit fault
Physical damage to the charge coupler assembly

How to diagnose and fix it

Inspect the charge coupler and sensor connector for corrosion, moisture, or physical damage
Disconnect the sensor and measure its resistance; compare to specifications
Check the sensor signal circuit for a short to ground using a multimeter
Inspect the wiring harness for chafing, pinches, or breaks along its routing
Test the control module's reference voltage and ground at the sensor connector
Replace the battery charger coupler temperature sensor if faulty
Clear the diagnostic trouble codes and verify the repair with a test drive or charging cycle

Common misdiagnosis of coupler sensor faults

A low signal code often results from a shorted sensor rather than a wiring issue, so resistance testing is more reliable than visual inspection alone.
Moisture ingress at the charge coupler connector can mimic a failed sensor and cause intermittent low signal codes that disappear after drying.
On some vehicles, the coupler temperature sensor is integrated into the charge port assembly and cannot be replaced separately, requiring a larger repair.
The control module may set this code if the sensor circuit is open, but a low signal specifically points to a short or sensor failure, not an open circuit.
Charging system faults can cause cascading codes, so always check for related codes in the battery management system before replacing parts.

Can I keep driving with P2E51?

If the vehicle is a plug-in hybrid or electric model, avoid charging until the fault is repaired because a failed temperature sensor can lead to overheating or charging interruption. The vehicle may still be driven using the internal combustion engine, but reduced electric range is likely.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.