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Porsche 997: How to Reset ECU

Resetting the ECU (Engine Control Unit) is a basic task, commonly prescribed when modifying your vehicle or doing any sort of work with sensors (MAF and O2 in particular). Do it once, and you'll never forget it.

By Jacob Stumph - April 27, 2015

This article applies to the Porsche 997 (2005-2012).

The Engine Control Unit (ECU) is the computerized brain of the car that controls the functionality of the engine. Within the engine, the ECU controls the air/fuel ratio, ignition and valve timing and control, and idle speed among others. Resetting your Porsche 997's ECU is useful in helping the car adapt to new modifications and gets rid of unwanted check engine light prompts. This article outlines the procedure to reset the ECU of your 997.

Materials Needed

  • 10mm socket, and ratcheting wrench
  • Scotch-brite pad (optional)
  • Rag (optional)
  • Painter's tape

Step 1 – Open the battery access box

The battery is enclosed in the upper plastic shrouding in the engine bay. There are two twist tabs on the cover that need to be unlatched to access the battery.

Figure 1. Battery box twist tabs highlighted in red.

Step 2 – Remove negative terminal from battery

Using a 10 millimeter socket wrench, undo the negative terminal for the battery and set the terminal aside. Make sure that the terminal does not contact the battery post or sparking will occur. You can use some painter's tape to secure the terminal to the side of the battery.

Pro Tip

If your battery posts are looking dirty or contaminated, you can take a Scotch-brite pad or sandpaper and gently scuff them up to clean them. Wipe off any excess with a rag.

Figure 2. Negative terminal moved aside.

Step 3 – Reconnect negative terminal

After 10 minutes or so, the computer has had sufficient time to "die," which means that the terminal can be reconnected.

Pro Tip

Fasten until snug; you don't need to crank down on the terminal or else you could wear out the fastener.

Step 4 – Start engine

With that done, button up the battery box and start the vehicle, letting it idle for a few minutes. It is not uncommon for the idle to initially be a bit nervous, so allow it a minute or two to settle.

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