What Is p0603 Code on 7.3 Powerstroke – [Quick Fixing]

A p0603 code 7.3 Powerstroke occurs when there’s an error in the Keep Alive Memory (KAM). The code means that the PCM isn’t receiving settings from the KAM. Loose connections or a damaged battery are the leading causes of this failure. The code’s common symptom is the check engine light turning on.

Code p0603 is a powertrain control module (PCM)-related trouble code displayed when the KAM fails. KAM is crucial to the car’s smooth operations because it stores information about the many systems that PCM controls.

To diagnose the KAM or PCM failure, you should inspect the connections, battery terminals and check for water damage. After diagnosing the issue, you can replace parts and wires or update the PCM software to remove the trouble code.

P0603 Code 7.3 Powerstroke
Error Code P0603

P0603 Code 7.3 Powerstroke

Code P0603 indicates that the 7.3 Ford Powerstroke engine is experiencing problems. Usually, when you see the code, it means an error has occurred in the Internal Control Module Keep Alive Memory (KAM). KAM’s function is to record and store the preferences of a driver in different road conditions.

The Powertrain Control Module (PCM) controls several critical systems of the car and comes with preset characteristics. However, the manufacturer settings rarely match a user’s driving style. Hence, the data stored in the KAM helps tailor the settings to match the driving style of a particular user.

If an error occurs in KAM, the PCM is unable to get the recorded information and can’t provide a smooth driving experience for the user. The PCM continually runs diagnostic tests, and when it is unable to retrieve settings from KAM, code p0603 is displayed.

Sometimes a PCM failure, such as the one caused by a KAM malfunction, can cause a p1249 code 6.7 Powerstroke. If you would like to know more about that, I went into detail about it in this article.

What Issues Cause Code P0603 On 7.3 Powerstroke?

In my experience, p0603 code may result from various issues. Some of these issues include;

  1. Poor battery connections or corroded terminals.
  2. The Keep Alive Memory could be receiving insufficient energy from a discharged battery.
  3. Issues with the charging system or a damaged battery
  4. The Keep Alive Memory or Powertrain Control Module could be faulty due to water intrusion.
  5. Shortcirciuted Keep Alive Memory or battery
  6. The Keep-Alive Power circuit could be open
  7. Outdated PCM software

How Do You Identify Code P0603 On 7.3 Powerstroke?

Most of the time, if you’re keen, you can see the signs of an impending code p0603. The most common ones include;

  1. Difficulty starting the engine.
  2. Various check engine indicators turn on.
  3. Unusual fuel consumption patterns
  4. Random engine stalls or misfires
  5. The malfunction indicator lamp turns on.
  6. Choppy acceleration and rough handling
  7. Transmission shifting issues

Even if you notice some or all of these symptoms, you can’t be sure the issue is a p0603 code without using an OBD-II scanner. For example, a p2263 code 6.4 Powerstroke, which I have written about in this article, can make starting the engine difficult and cause acceleration problems.

SYMPTOMS OF A BAD ECM (ENGINE CONTROL MODULE) >> Check out the video below:

What Are The Effects Of Code P0603 On 7.3 Powerstroke?

The PCM is linked to and affects the operations of several crucial car processes like ignition, transmission, and air/fuel mixing. Hence, if code P0603 occurs and remains unresolved, the engine may stall.

KAM stores the performance attributes of the car. Hence, if it fails, timing errors will occur in the transmission and engine, causing wear and also poor, uncomfortable shifting.

The Powertrain Control Module is linked to the OBD-II system of the car, meaning failure can potentially lead to worse codes affecting that system.

How To Troubleshoot And Fix Code P0603 On 7.3 Powerstroke?

Since several factors can cause code P0603, diagnosing it can be challenging. Here’s my step-by-step guide on how to diagnose your vehicle if you suspect a code P0603;

  1. The first thing is to get the right tools for the diagnosis. These include;
  2. OBD-II scanner
  3. Voltmeter
  4. Battery charger
  5. Hand tools such as screwdrivers and wrenches
  6. Vehicle repair manual
  7. Charge the battery before starting the tests.
  8. Check for corrosion or loose wiring near the battery terminals and the KAM power circuit. Inspect the ground connections as well.
  9. Inspect the battery charging circuit.
  10. Check the wiring going into the fuse and the PCM for loose or open wires.
  11. Test the voltage across the PCM according to the repair manual.
  12. Check for any signs of water intrusion or damage in the PCM.
  13. Reset the PCM to factory settings and try running it to see if the code reappears.

How To Fix p0603 Code on 7.3 Powerstroke? (6 Quick Fix)

Depending on what you discover to be the problem with your Powerstroke engine, there are several repairs that can solve code P0603. These include;

  1. Clean the battery terminals and remove any corroded wires. Ensure that the connections are sturdy and there are no loose connections.
  2. If the problem was the KAM wiring, replace it with a new set of wires. Close all open connections.
  3. Replace the battery if it is damaged or charge it if it has fully discharged.
  4. Update your PCM software. If the issue was software related, the latest update should fix it.
  5. Replace your PCM if it was the issue.
  6. In some cases, removing any after-market chips or tuners will solve the code.

Some of these repairs are too complicated for the average person to do on their own, so I recommend going to a certified mechanic.

What’s The Cost Of Fixing The P0603 Code?

On average, a PCM costs about $900, so when I have to replace it, repair costs are above $1000. If the fix involves replacing wires or cleaning corroded battery terminals, the expense is about $100. Battery replacement costs lie between $50 and $250, including labor costs.

frequently asked questions (FAQs)

Apart from the p0603 code, several other codes also indicate problems with a car’s electronic control unit. Here are some of my answers to the most common questions.

1. Trouble Codes Related To Code P0603?

Several other codes fall in the same category as code p0603. They include;

  • P0606 – Displayed when an error occurs in the PCM processor
  • P0600 – Indicates a failure in communication between the PCM and the myriad of sensors connected to it.
  • P0605 – This code shows a failure of the Internal Control Module’s Read Only Memory.
  • P0607 – Signals a performance error in the control module.

2. Can Other Trouble Codes Occur Together With P0603?

Yes, several diagnostic codes can occur simultaneously. If any codes appear together with P0603, then I suggest you start by solving them. Sometimes the P0603 disappears when you fix the other trouble codes.

Take Away

Code p0603 indicates a Keep Alive Memory error which may be due to issues such as loose connections, discharged or damaged battery, or even a faulty PCM.

Since the error can cause issues such as rough gear changes and engine stalls, it is wise to troubleshoot and fix it as soon as you see any symptoms. Diagnosing and solving the p0603 code 7.3 Powerstroke is fairly easy and cheap if you want to do it yourself.

If you’re uncomfortable doing the repairs yourself or have too many trouble codes simultaneously, I suggest visiting an auto repair shop.

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Mahir Ahmed


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