AutoCodes – Toyota – P0604 2002 Toyota Highlander

P0604 2002 Toyota Highlander Code - Internal Control Module Random Access Memory Error

Quick Answer

The Engine Control Module (ECM) continuously monitors its internal memory status, internal circuits, and output signals to the throttle actuator. Common causes include Faulty Engine Control Module (ECM), Engine Control Module (ECM) Harness power supply circuit is open or shorted, Engine Control Module (ECM) Programming. 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: P0604 2002 Toyota Highlander indicates Internal Control Module Random Access Memory Error.
Common causes: Common causes include Faulty Engine Control Module (ECM), Engine Control Module (ECM) Harness power supply circuit is open or shorted, Engine Control Module (ECM) Programming.
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 1,794

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 Jun 14, 2020

Description
Possible Causes
How To Fix
Tech Notes
Cost to Diagnose
FAQs
Comments
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Code P0604 2002 Toyota Highlander Description

The Engine Control Module (ECM) continuously monitors its internal memory status, internal circuits, and output signals to the throttle actuator. This selfâˆ’check insures that the ECM is functioning properly. If any malfunction is detected, the ECM will set the code and illuminate the engine light.
The ECM memory status is diagnosed by internal mirroring of the main CPU and the sub CPU to detect Random Access Memory (RAM) errors. The two CPUs also perform continuous mutual monitoring. The ECM illuminates the MIL and sets a DTC if: 1) outputs from the two CPUs are different or deviate from the standards, 2) the signals sent to the throttle actuator deviate from the standards, 3) a malfunction is found in the throttle actuator supply voltage, and 4) any other ECM malfunction is found.

OBDII Code P0604 2002 Toyota Highlander - Internal Control Module Random Access Memory Error - AutoCodes.com — P0604 2002 Toyota Highlander Code - Internal Control Module Random Access Memory Error

What does this mean?

What are the Possible Causes of the DTC P0604 2002 Toyota Highlander?

Faulty Engine Control Module (ECM)
Engine Control Module (ECM) Harness power supply circuit is open or shorted
Engine Control Module (ECM) Programming

How to Fix the DTC P0604 2002 Toyota Highlander?

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 does this mean?

Code Tech Notes

Check the ECM fuse, if fuse is OK try erasing the code first and if the code comes back you may have to reprogram or replaced the ECM.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P0604 2002 Toyota Highlander 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 P0604 2002 Toyota Highlander code?

Need more information on how to fix the P0604 2002 Toyota Highlander code? Get Access to Factory Service Manuals

Need Help with the 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.

Frequently Asked Questions about P0604 2002 Toyota Highlander Code

1. What does OBDII code P0604 on a 2002 Toyota Highlander mean?

The code P0604 indicates an Internal Control Module Random Access Memory Error.

2. What are common symptoms of P0604 in a 2002 Toyota Highlander?

Common symptoms include engine stalling, rough idling, poor acceleration, and the illumination of the Check Engine Light.

3. What are possible causes of the P0604 code in a 2002 Toyota Highlander?

Potential causes include a faulty Engine Control Module (ECM), damaged wiring or connectors, software issues, or a low vehicle battery.

4. How can I diagnose the P0604 code in my 2002 Toyota Highlander?

Diagnosing the code typically involves using an OBDII scanner to retrieve the code, checking the ECM for any visible damage, inspecting wiring and connectors for faults, and testing the battery voltage.

5. Can I still drive my 2002 Toyota Highlander with the P0604 code present?

It is not recommended to drive the vehicle with the P0604 code present, as it can lead to potential performance issues and further damage to the engine.

6. How do I repair the P0604 code in my 2002 Toyota Highlander?

Repair options may include replacing the ECM, repairing or replacing damaged wiring or connectors, updating the ECM software, or addressing any underlying battery issues.

7. Can I reset the P0604 code in my 2002 Toyota Highlander by disconnecting the battery?

While disconnecting the battery may temporarily clear the code, it is not a permanent solution. It is essential to diagnose and address the root cause of the code to prevent it from reoccurring.

8. How much does it cost to repair the P0604 code in a 2002 Toyota Highlander?

The cost of repair can vary depending on the specific cause of the code and the labor rates in your area. It is recommended to consult with a trusted mechanic for an accurate estimate.

9. Is the P0604 code a common issue in 2002 Toyota Highlanders?

While the P0604 code is not extremely common, it can occur in older vehicles like the 2002 Toyota Highlander due to various factors such as age, wear and tear, or electrical issues.

10. Can I prevent the P0604 code from appearing in my 2002 Toyota Highlander?

Regular maintenance, ensuring proper battery health, and addressing any warning signs promptly can help prevent the occurrence of the P0604 code in your 2002 Toyota Highlander.