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AutoCodes – Generic – P1EC4

P1EC4 Code - Hybrid/EV Battery Pack Heater Transistor Stuck Off

Quick Answer

The hybrid/EV battery contains 5 high voltage contactors and 2 transistors. Common causes include Faulty Battery Energy Control Module, Battery Energy Control Module harness is open or shorted, Battery Energy Control Module circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means
P1EC4 indicates Hybrid/EV Battery Pack Heater Transistor Stuck Off.
Common causes
Common causes include Faulty Battery Energy Control Module, Battery Energy Control Module harness is open or shorted, Battery Energy Control Module circuit poor electrical connection.
Severity
High - diagnose this code as soon as possible.
Can I drive?
Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
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Code Popularity 2,406
How popular is this code, among other codes? Low
What is this?
Table of contents Created and updated by William Orellana on Apr 25, 2020
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Code P1EC4 Description

The hybrid/EV battery contains 5 high voltage contactors and 2 transistors. The high voltage contactors and transistors allow the high voltage DC batteries to be connected to the vehicle or safely contain the high voltage DC within the hybrid/EV battery assembly. The 5 high voltage contactors consist of a main positive high voltage contactor, main negative high voltage contactor, charge positive high voltage contactor, charge negative high voltage contactor and multi-function high voltage contactor. The 2 transistors consist of the precharge transistor and heater transistor. The contactors and transistors close and open in a specific sequence controlled by the hybrid/EV powertrain control module 2. The hybrid/EV powertrain control module 2 supplies voltage to the control circuit for the high voltage contactors/transistors. Ground is provided through the case ground.
OBDII Code P1EC4 - Hybrid/EV Battery Pack Heater Transistor Stuck Off - AutoCodes.com
P1EC4 Code - Hybrid/EV Battery Pack Heater Transistor Stuck Off
What does this mean?

What are the Possible Causes of the DTC P1EC4?

  • Faulty Battery Energy Control Module
  • Battery Energy Control Module harness is open or shorted
  • Battery Energy Control Module circuit poor electrical connection

How to Fix the DTC P1EC4?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1EC4 code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

Need more information about the P1EC4 code?

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Need Help with the Code?

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Information for Specific Makes

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1EC4 Code

What does the OBDII code P1EC4 mean?

The P1EC4 code indicates that the hybrid or EV battery pack heater transistor is stuck in the "off" position, preventing proper heating of the battery pack.

What are the symptoms of a P1EC4 code?

Symptoms may include poor battery performance in cold weather, reduced vehicle range, or an illuminated check engine light.

What causes the P1EC4 code?

Common causes include a malfunctioning battery pack heater, a failed transistor, damaged wiring, or a fault in the battery control module.

Can I still drive my vehicle with a P1EC4 code?

While the vehicle may still be drivable, battery performance may suffer in cold temperatures. It's best to address the issue promptly to avoid further damage.

How is the P1EC4 code diagnosed?

A technician will use a scan tool to confirm the code, inspect the battery heater system, check for wiring issues, and test the transistor's operation.

What repairs are needed to fix the P1EC4 code?

Repairs may include replacing the battery pack heater, repairing damaged wiring, or replacing a faulty transistor or control module.

How much does it cost to fix the P1EC4 code?

Repair costs vary but can range from $200 to $1,500 depending on the specific part that needs replacement and labor costs.

Can a software update fix the P1EC4 code?

In rare cases, a software update to the battery control module may resolve the issue if it's caused by a programming error.

What happens if I ignore the P1EC4 code?

Ignoring the code may lead to poor battery performance, reduced vehicle efficiency, and potential long-term damage to the battery pack.

How can I prevent the P1EC4 code from occurring?

Regular maintenance, inspecting the battery heater system, and addressing electrical issues promptly can help prevent this code.

Discuss the causes and fixes for P1EC4 OBDII Code

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