AutoCodes – Lexus – P0A77 Lexus

P0A77 Lexus Code - Generator Phase W Current High

Quick Answer

The inverter converts the high-voltage direct current of the HV battery and the alternating current for the MG1/MG2. Common causes include Faulty Inverter With Converter Assembly, Inverter With Converter Assembly harness is open or shorted, Inverter With Converter Assembly 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: P0A77 Lexus indicates Generator Phase W Current High.
Common causes: Common causes include Faulty Inverter With Converter Assembly, Inverter With Converter Assembly harness is open or shorted, Inverter With Converter Assembly 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 1,334

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on May 11, 2019

Description
Possible Causes
How To Fix
Cost to Diagnose
Comments
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Code P0A77 Lexus Description

The inverter converts the high-voltage direct current of the HV battery and the alternating current for the MG1/MG2. The inverter contains a three-phase bridge circuit, which consists of 6 power transistors each for the MG1 and the MG2, in order to convert the direct current and the three-phase alternating current.
The HV control ECU controls the actuation of the power transistors.
The inverter transmits information that is necessary for effecting control, such as the amperage and voltage, to the HV control ECU.
The motor inverter current sensors detect the amperage that flows through the V and W phase cables between the inverter and MG1/MG2. The inverter transmits information that is necessary for effecting control, such as the amperage and voltage, to the HV control ECU.
The HV control ECU monitors the inverter current sensors to detect a malfunction in the sensor system.

OBDII Code P0A77 Lexus - Generator Phase W Current High - AutoCodes.com — P0A77 Lexus Code - Generator Phase W Current High

What does this mean?

What are the Possible Causes of the DTC P0A77 Lexus?

Faulty Inverter With Converter Assembly
Inverter With Converter Assembly harness is open or shorted
Inverter With Converter Assembly circuit poor electrical connection

How to Fix the DTC P0A77 Lexus?

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 P0A77 Lexus 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 P0A77 Lexus code?

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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.