What Is P0603 Code On 7.3 Powerstroke: How To Fix?

Ford notifies users about their 7.3L engine’s condition giving several DTC (Diagnostic Trouble Codes). The P0603 is one of them & it carries its own meaning as well. 

If you’re getting this error code & don’t know what it means, this article is for you. Stay tuned as I’ll be discussing everything from symptoms to solving methods to help you with the code. 

What Does P0603 Code Means On 7.3L Powerstroke?

P0603 is one of the most common trouble codes of Ford’s 7.3L engine. By definition, the code P0603 means Internal Control Module Keep Alive Memory (KAM) Error.

The Keep-Alive Memory (KAM) acts like an Artificial Intelligence (AI) that learns from every drive cycle & it includes engine settings you change while driving on different types of road. Later on, these data are used by the PCM. 

The PCM tries to retrieve data from Keep Alive Memory (KAM) to give optimal performance according to the user’s preferences. When it fails to do so even after several attempts, it generates the error code P0603. 

Interesting Fact: The KAM is a special kind of RAM that stores data permanently as the battery directly powers it. 

Symptoms Of Getting The P0603 Code On A 7.3

The DTCs are generous enough to let us know about their existence through their symptoms. Expect to have the DTC P0603 if you’re noticing these symptoms mentioned below:

  1. CEL (Check Engine Light) Is On
  2. Engine Stalling Issue 
  3. The Engine Misfires Sometimes
  4. The engine is Hard To Start 
  5. Rough Acceleration & Idling 
  6. Dramatically Increased Fuel Consumption 

These symptoms are not absolute. Get yourself an OBD-II Code Scanner for less than $50 to make sure it’s a P0603 code. 

The Causing Factors Of The Error Code P0603

One of the most common causes of getting this DTC is using aftermarket engine management products. Besides, the following factors can contribute to generating the error code P0603:

  1. Keep Alive Memory is Not Receiving Enough Power
  2. Battery or Keep Alive Memory Has Shorted Out
  3. Loose Connection & Battery Terminal Corrosion
  4. Malfunctioning Wiring Of Keep Alive Memory (KAM) & Keep Alive Power (KAPWR)
  5. Damaged Keep Alive Memory or Powertrain Control Module 
  6. PCM Internal Fault Due To Water Intrusion 
  7. Faulty Battery & Charging System

How Serious Is The Code P0603 On 7.3 Powerstroke

The results of the error code P0603 differ from engine to engine. From Zero-Problem to damaging the engine entirely is possible with the DTC P0603. Take your next solving step & read the following segment of this article. 

How To Solve P0603 Error Code On 7.3L Powerstroke?

Like most other DTC, P0603 can be diagnosed within simple do-it-yourself (DIY) works. Make sure to get the following equipment before troubleshooting this code: 

  • A Battery Charger, Flashlight & Multimeter 
  • An OBD-II Code Scanner

Let’s assume you’re ready with the equipment mentioned above. So, without further ado, let’s get started with the solution to the DTC P0603:

Wait or Remove Aftermarket Engine Management Products 

Engineering the truck with aftermarket engine management products is a common practice. If you’ve installed any chip to boost your engine performance, it’s common & normal to have the error code P0603. 

To remove the code permanently, you’ve to remove every aftermarket engine management product. Fortunately, the code will go away by itself after some days of installing these products.

Check Your Battery Health 

Use the car battery charger & fill the battery entirely. Now remove the code with the scanner tool & normally drive your car for one week or so. 

If the DTC reappears, it means the battery cannot produce enough power to KAM while it’s charged by the truck itself.  

Replace the battery & the error code should be solved permanently. Before replacing, you can give it a second chance via replacing the writing first. 

Inspect Battery Related Wiring

Check your battery cables thoroughly & look for damage, corrosion & lose connections. If you get anything mentioned, replace those wiring & your battery problem should be fixed.

Check For PCM Wiring Leakage

The PCM wiring can also play a crucial role in generating this error code. Check if the power supply line is providing enough voltage (12.5V) to the PCM. 

Even if the voltage shows 12.5V, try bending the wire & check again. If the voltage changes – it indicates the wire is broken or loosen. Try replacing the power supply line & the error code should be gone. 

Update To The Latest PCM Software Version 

Manufacturers often release PCM software updates without mass awareness in the beginning. Running the PCM on outdated/older software can lead to the P0603 error code.

Head over to your nearest dealer & update to the latest PCM software version. If you’re lucky enough, you should not notice the error code anymore. 

Replace Your Powertrain Control Module (Rare Case)

Even after doing everything right & everything is working correctly, the PCM (Powertrain Control Module) seems to be the main culprit. 

Replacing the PCM will solve the error code P0603 for sure. If you’re new to Ford’s 7.3L engine, I won’t encourage you to replace the PCM on your own. 

Hire any professional to do the work & pay them according to their hourly rate. Make sure to buy the PCM by yourself to save some bucks. 

How Much Does The DTC P0603 Cost To Solve?

The fixing cost of the DTC P0603 depends on the solving method. If you’re doing basic wire replacement, the cost shouldn’t exceed $50. 

On the other hand, replacing the battery will cost you around $200. Finally, replacing the PCM will cost you $500 to $1500+($250 labor cost). 

Common Mistakes While Solving The P0603 Code

It’s possible to encounter mistakes if you’re new to Ford’s 7.3L. Make sure to avoid the following common mistakes while solving the P0603 error code:

  • Reading The Voltage Wrong While Testing The Power Supply Line
  • Not Testing Everything (Wirings, Connectors & Harness) Before Testing & Replacing The PCM. 

Additional Comments To Consider Regarding The P0603 Code

It’s normal to get the DTC if you’ve recently disconnected the battery from the truck. Wait for some days & the code will disappear on its own. 

If it doesn’t, make sure to check everything mentioned in this article to safeguard your wallet & engine’s future health. 

Conclusion 

I hope this article was helpful enough to know the DTC P0603 in-depth. Now you can spot & diagnose this error code without losing your sweat figuring out the exact problems.

Don’t hesitate to get professional help when it’s needed. You’ll be doing more harm to your 7.3L Powerstroke if you’re unwilling to get professional just because of the high Hourly Rate.