How to Fix a P0605 Code: An Easy Step-by-Step Guide

AvatarByCarl Frisch

P0605 is an OBD-II diagnostic trouble code (DTC) that indicates a malfunction in the internal control module memory. It is typically caused by a fault with the vehicle’s Engine Control Module (ECM) or Electronic Control Unit (ECU). In order to fix this code, you need to diagnose and repair the underlying cause of the problem.

First, you should check for any stored trouble codes in the ECM/ECU memory. This can be done with an OBD-II scanner connected to your vehicle’s onboard computer. Once any stored codes are identified, they should be addressed first before proceeding with fixing the P0605 code.

Next, you should inspect all wiring and connectors associated with the ECM/ECU for any damage or loose connections. If any issues are found, they should be repaired or replaced as necessary. Additionally, it may also be necessary to check for any software updates available for your vehicle’s computer system.

Finally, if all wiring and connectors are in good condition and no other codes are present, you may need to replace the ECM/ECU itself or have it professionally repaired. If this is not possible, then you may need to install a new one altogether.

Overall, fixing a P0605 code requires some knowledge of vehicles’ onboard computer systems as well as skill in diagnosing and repairing electrical problems.

How to Diagnose a P0605 Code?

Diagnosing a P0605 code can be tricky, but it’s important to get it right. The first step is to check for diagnostic trouble codes (DTCs) that may be related. If you do find any, it’s important to inspect and troubleshoot the related components before moving on. After that, you should inspect the wiring harness for any damage or loose connections, and then test the powertrain control module (PCM).

Common Causes of a P0605 Code

P0605 codes are typically caused by a faulty PCM or damaged wiring harness. In some cases, however, there may be other causes such as a defective ignition switch or failed crankshaft position sensor.

How to Fix a P0605 Code?

The most common fix for a P0605 code is to replace the PCM. If the wiring harness is damaged or has loose connections, then it should be repaired or replaced as well. In some cases, resetting the ECU may also help resolve the issue.

Other Potential Fixes for a P0605 Code

In addition to replacing or repairing the PCM and wiring harness, resetting the ECU can also help resolve any issues with a P0605 code. This can typically be done by disconnecting the battery and waiting at least 10 minutes before reconnecting it.

What Can Happen if You Don’t Fix A P0605 Code?

If you don’t fix a P0605 code, your vehicle may experience reduced engine performance and decreased fuel economy over time due to incorrect data being sent from the PCM to other systems in your vehicle. It could also lead to more serious issues such as a failure of emissions tests or complete engine failure if left unchecked for too long.

Signs & Symptoms of a Bad PCM

When your car has a bad PCM, there are certain signs and symptoms that may indicate the problem. The most common signs and symptoms of a bad PCM include difficulty starting the engine, poor vehicle performance, unusual noises under the hood, and a check engine light on. If you experience any of these issues, it’s important to have it checked out by an experienced mechanic as soon as possible.

Tips for Diagnosing and Repairing A P0605 Code

Diagnosing and repairing a P0605 code can be tricky but following these tips can help make the process easier. First, check all connections on the PCM to ensure they are properly connected. Next, read all related trouble codes before proceeding with repairs to ensure that you are properly addressing the issue. Finally, always follow manufacturer directions when replacing any parts to make sure you get the best results.

Common Mistakes When Diagnosing and Repairing A P0605 Code

When diagnosing and repairing a P0605 code there are some common mistakes that should be avoided in order to avoid further damage to your vehicle or costly repairs. The most common mistake is not properly reading all related trouble codes before proceeding with repairs as this can lead to improper diagnosis or incorrect parts being installed which can worsen the problem. Additionally, failing to follow manufacturer directions when replacing parts can also result in costly repairs or further damage to your vehicle.

FAQ & Answers

Q: What is a P0605 Code?
A: A P0605 code is an indication of a fault in the internal control module memory. It is usually caused by a malfunction in the PCM or wiring harness.

Q: What are the Common Causes of a P0605 Code?
A: The common causes of a P0605 code include a faulty PCM, damaged wiring harness, or other related components.

Q: How to Fix a P0605 Code?
A: To fix a P0605 code you may need to replace the PCM, repair or replace the wiring harness, or reset the ECU.

Q: What Can Happen if You Don’t Fix A P0605 Code?
A: If you don’t fix the P0605 code it can lead to poor vehicle performance and engine difficulty starting. It may also cause unusual noises under your hood and your check engine light could turn on.

Q: What are the Tips for Diagnosing and Repairing A P0605 Code?
A: Tips for diagnosing and repairing a P0605 code include checking all connections on the PCM, reading all related trouble codes before repairs, and always following manufacturer directions when replacing parts. Common mistakes when diagnosing and repairing this issue include not reading all related trouble codes before proceeding with repairs and not following manufacturer directions when replacing parts.

To fix a P0605 code, you should first check the powertrain control module (PCM) for any loose or corroded connections. If no issues are found, then you should inspect the wiring and sensors associated with the PCM. If all wiring and connectors appear to be in good condition, then you may need to replace the PCM itself. It is important to ensure that the correct replacement part is purchased and installed correctly in order to avoid any further issues.

Author Profile

Carl Frisch
Carl Frisch
With more than 30 years in the bicycle industry, I have a strong background in bicycle retailing, sales, marketing and customer service. I have a passion for cycling and a dedication to excellence. As a manager, I worked diligently to increase my capabilities and responsibilities, managing up to eleven mechanics (at Palo Alto Bicycles) and later as a working partner in my own store.

As the shop owner of Spoke n’ Word Cycles in Socorro, NM, the success of the mission was my responsibility, which I pursued passionately since we opened in 2003 through the spring of 2011. I am adept at managing owned and loan inventory, preparing weekly & annual inventory statements, and managing staff. The role as managing partner also allowed me tremendous freedom. I used this personal freedom to become more deeply involved in my own advancement as a mechanic, to spearhead local trail building, and advocating for cycling both locally and regionally.

As a mechanic, I have several years doing neutral support, experience as a team mechanic, and experience supporting local rides, races, club events. I consistently strive to ensure that bicycles function flawlessly by foreseeing issues and working with the riders, soigners, coaches and other mechanics. Even with decades of experience as a shop mechanic and team mechanic, and continue to pursue greater involvement in this sport as a US Pro Mechanic, and UCI Pro Mechanic.

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