How I Checked My Ford Kuga PHEV 12V Battery with FORScan

I own a 2021 Ford Kuga 2.5 PHEV, and one problem kept coming back: the 12V battery was losing charge too easily.

The car is often used for short trips and sometimes stays parked for several days. Instead of immediately replacing parts, I wanted to see what the car itself could tell me.

That's where FORScan became useful.

What I used

For the diagnosis I used:

• a Windows laptop
• FORScan
• an OBD2 adapter compatible with Ford vehicles
• my Ford Kuga PHEV

After connecting the adapter to the OBD2 port, FORScan allowed me to look at information that a basic battery tester alone cannot show.

Why check the 12V battery on a PHEV?

A plug-in hybrid still depends heavily on its 12V battery.

The high-voltage traction battery doesn't eliminate the need for the conventional battery. The 12V system is involved in powering electronics and allowing the vehicle's systems to start correctly.

That means a weak 12V battery can cause strange behaviour even when the large hybrid battery has plenty of charge.

What I checked with FORScan

My goal wasn't simply to read fault codes.

I wanted to understand the condition of the 12V system and check the information available from the Battery Monitoring System.

FORScan made it possible to inspect the vehicle data directly instead of guessing from symptoms alone.

This was particularly useful because the battery problem was intermittent: after short trips or a period without using the car, the battery could become noticeably weak.

One important lesson: the BMS matters

Ford uses a Battery Monitoring System to keep track of the 12V battery.

If the battery is replaced, the BMS should know that a new battery has been installed. Otherwise, the vehicle may continue managing the charging system based on information associated with the old battery.

After working on my Kuga's battery, I also performed the BMS reset with FORScan.

What I learned

The biggest lesson from this experience was simple:

Don't diagnose a modern car battery only by looking at whether the engine starts.

OBD2 diagnostics can provide additional information about what the vehicle is seeing and can help separate a battery problem from other electrical issues.

FORScan is particularly interesting for Ford owners because it provides access to much more vehicle-specific information than a basic generic OBD2 reader.

I documented the procedure I used, including the connection and battery checks, in a more detailed guide on my site:

How to check a Ford Kuga PHEV 12V battery with FORScan

This is based on my own 2021 Ford Kuga 2.5 PHEV, so menus, parameters and behaviour can differ on other Ford models or model years.