AutoCodes – Toyota – P0AA2 Toyota

P0AA2 Toyota Code - Hybrid Battery Positive Contactor Circuit Stuck Open

Quick Answer

The SMRs (System Main Relays) connect and disconnect the high-voltage power supply circuit in accordance with requests from the HV control ECU. Common causes include Faulty System Main Relay, System Main Relay harness is open or shorted, System Main Relay 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: P0AA2 Toyota indicates Hybrid Battery Positive Contactor Circuit Stuck Open.
Common causes: Common causes include Faulty System Main Relay, System Main Relay harness is open or shorted, System Main Relay 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 1,849

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
FAQs
Comments
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Code P0AA2 Toyota Description

The SMRs (System Main Relays) connect and disconnect the high-voltage power supply circuit in accordance with requests from the HV control ECU. To ensure a reliable operation, they consists of a total of 3 relays (1 for the negative side and 2 for the positive side).
To connect, SMR1 and SMR3 turn ON initially. Then, SMR2 turns ON and SMR1 turns OFF. This process protects the circuit from the high-voltage surge current by allowing the limit current to flow via the resistor. To disconnect, SMR2 and SMR3 turn OFF in that order. The HV control ECU checks that the relays have turned OFF properly.
The HV control ECU monitors the proper operation of the SMRs (CON1, CON2 and CON3) to check for a malfunction.

OBDII Code P0AA2 Toyota - Hybrid Battery Positive Contactor Circuit Stuck Open - AutoCodes.com — P0AA2 Toyota Code - Hybrid Battery Positive Contactor Circuit Stuck Open

What does this mean?

What are the Possible Causes of the DTC P0AA2 Toyota?

Faulty System Main Relay
System Main Relay harness is open or shorted
System Main Relay circuit poor electrical connection
Faulty HV control ECU

How to Fix the DTC P0AA2 Toyota?

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 P0AA2 Toyota 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.

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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.

Frequently Asked Questions about P0AA2 Toyota Code

1. What does the P0AA2 code mean for a Toyota hybrid vehicle?

The P0AA2 code indicates that the hybrid battery positive contactor circuit is stuck open, preventing proper electrical flow between the hybrid battery and the inverter.

2. What are the common symptoms of the P0AA2 code in a Toyota hybrid?

Symptoms may include reduced vehicle performance, warning lights on the dashboard, inability to start the vehicle, or error messages related to the hybrid system.

3. What causes the P0AA2 code in a Toyota hybrid?

The code is typically caused by a malfunctioning hybrid battery contactor, damaged wiring or connectors, or issues within the battery control module.

4. Can I drive my Toyota hybrid with the P0AA2 code?

Driving with this code is not recommended as it can lead to further damage and may prevent the hybrid system from functioning properly.

5. How is the P0AA2 code diagnosed?

A technician will use an OBDII scanner to retrieve the code, inspect the battery contactor circuit, check for damaged or corroded wiring, and verify the operation of related components.

6. How do you fix the P0AA2 code in a Toyota hybrid?

Repairs may involve replacing the hybrid battery contactor, repairing damaged wiring, or reprogramming the battery control module if necessary.

7. How much does it cost to repair the P0AA2 code on a Toyota hybrid?

Repair costs vary depending on the extent of damage, but replacing the hybrid battery contactor can range from $500 to over $1,000, plus labor costs.

8. What tools are needed to repair the P0AA2 code?

Specialized tools such as an OBDII scanner, multimeter, and hybrid system safety equipment are required for diagnosing and repairing the issue.

9. Can the P0AA2 code be related to a dead hybrid battery?

While the code itself refers to the contactor circuit, a failing hybrid battery can indirectly contribute to electrical issues that trigger this code.

10. Does the P0AA2 code require dealership service?

In many cases, repairs for hybrid system codes like P0AA2 are best performed at a dealership or by a qualified hybrid technician due to the complexity and safety concerns.