Faulty charging stop switch or sensor; Damaged or corroded wiring in the charging stop switch circuit; Loose or disconnected electrical connector at the switch or control module; Failed or malfunctioning control module that interprets the switch signal; Water intrusion or contamination in the switch or connector; Aftermarket accessories improperly wired into the circuit

DTC codes / P2Dxx · Hybrid propulsion / P2D79

P2D79Charging Stop Switch Circuit

Q: What does code P2D79 mean?

Charging Stop Switch Circuit. P2D79 indicates that the powertrain control module has detected a fault in the charging stop switch circuit, which is used to signal when charging should be halted or paused. The computer monitors the circuit for expected voltage changes and sets this code when the signal is missing, stuck, or outside the normal range.

P2D79 indicates that the powertrain control module has detected a fault in the charging stop switch circuit, which is used to signal when charging should be halted or paused. The computer monitors the circuit for expected voltage changes and sets this code when the signal is missing, stuck, or outside the normal range.

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
Charging system may fail to stop when commanded, leading to overcharging or battery stress
Inability to enable or disable charging features such as scheduled charging or battery conditioning
Reduced fuel economy or increased emissions in hybrid vehicles due to improper charging control
Possible auxiliary battery drain or electrical accessory malfunctions

Common causes, most likely first

Faulty charging stop switch or sensor
Damaged or corroded wiring in the charging stop switch circuit
Loose or disconnected electrical connector at the switch or control module
Failed or malfunctioning control module that interprets the switch signal
Water intrusion or contamination in the switch or connector
Aftermarket accessories improperly wired into the circuit

How to diagnose and fix it

Use a scan tool to verify the code and check for related faults in other modules
Visually inspect the charging stop switch and its connector for damage, corrosion, or loose pins
Test the switch operation with a multimeter to confirm it opens and closes correctly
Check the wiring harness for continuity and shorts between the switch and the control module
Verify power and ground supplies to the switch and control module
If the switch tests good, check for software updates or known issues from the manufacturer
Replace the faulty switch or repair wiring as needed, then clear codes and verify the repair

Charging stop switch circuit pitfalls

A charging stop switch circuit fault can be caused by a simple loose connector that is often overlooked during diagnosis.
The code may set intermittently due to temperature-related resistance changes in the switch or wiring, making it hard to reproduce.
On some vehicles, the charging stop switch is integrated into a larger assembly, so the entire component may need replacement rather than just the switch.
This code does not always mean the switch itself has failed; wiring issues or control module faults are common misdiagnosis traps.
Aftermarket electrical accessories tapped into the circuit can introduce noise or voltage drops that trigger this code without any component failure.

Can I keep driving with P2D79?

The vehicle is generally safe to drive with this code, but avoid relying on charging features that may be affected. Have the fault diagnosed soon to prevent potential battery overcharging or electrical system stress.

Tools that help

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