MajorCommonElectrical

Mitsubishi Outlander: PHEV 12V Auxiliary Battery Premature Failure

PHEV 12V Auxiliary Battery Premature Failure is a common electrical fault on the Mitsubishi Outlander on the 2013 onward cars, and we rate it major. Putting it right costs ≈A$170 to ≈A$410 at independent workshop rates, shown as an approximate guide in Australian dollars. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 47 documented faults on the Mitsubishi Outlander.

Vehicle: Mitsubishi Outlander
Only on: plug-in
Years: 2013 onward
Fuel: hybrid
Gearbox: auto
System: Electrical

This page covers the Mitsubishi Outlander as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Mitsubishi Outlander faults47 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the 12V battery yet. We would rather show none than show a picture of a different part.

What goes wrong

The Outlander PHEV relies on a conventional 12V lead-acid auxiliary battery to power control systems, including the high-voltage battery management module. This 12V battery drains faster than on conventional vehicles because PHEV control electronics draw current continuously even when the traction battery appears to supply the load. Battery life is typically 2–4 years rather than the 4–6 years expected on a conventional vehicle. A failed 12V battery can prevent the high-voltage system from initialising, leaving the vehicle unable to start in either electric or petrol mode.

What you would notice

Vehicle fails to respond to key fob or start button
All dash warning lights illuminate simultaneously on start attempt
EV system fails to initialise despite high-voltage battery being charged
12V battery voltage below 11.5V measured with a multimeter

How to check it

Where to look. Under bonnet — front right of engine bay adjacent to brake fluid reservoir

Test the 12V auxiliary battery voltage and cold cranking amps with a battery tester.
Check the battery age via the date stamp on the case.
Inspect the battery hold-down and terminals for corrosion.
Ask when the 12V battery was last replaced.

Parts involved: 12V battery.

What it costs to put right

≈A$170 to ≈A$410 at independent workshop rates, shown as an approximate guide in Australian dollars. That is for this job on its own, not for the car.

An estimate, converted to Australian dollars, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

“When was the 12V auxiliary battery last replaced?”
“Has the vehicle ever failed to start or shown unexplained warning lights?”
“Has the car sat unused for extended periods?”

Now check the Mitsubishi Outlander you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car still has money owing on it, has been written off or reported stolen, what kms it showed in past sale ads, whether it has had accident repair claims and what it is worth today. That comes from the official records for that plate. Enter the plate and its state for the A$17.90 Vehicle Check, or the full history from A$24.99.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Mitsubishi Outlander buyer questions

Is phev 12v auxiliary battery premature failure serious on a Mitsubishi Outlander?

We rate it major and common on the Mitsubishi Outlander. The Outlander PHEV relies on a conventional 12V lead-acid auxiliary battery to power control systems, including the high-voltage battery management module. This 12V battery drains faster than on conventional vehicles because PHEV control electronics draw current continuously even when the traction battery appears to supply the load. Battery life is typically 2–4 years rather than the 4–6 years expected on a conventional vehicle. A failed 12V battery can prevent the high-voltage system from initialising, leaving the vehicle unable to start in either electric or petrol mode.

How much does it cost to fix on a Mitsubishi Outlander?

≈A$170 to ≈A$410 at independent workshop rates, shown as an approximate guide in Australian dollars. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Mitsubishi Outlander years are affected?

Our research records this fault on the 2013 onward Mitsubishi Outlander. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

Test the 12V auxiliary battery voltage and cold cranking amps with a battery tester. Check the battery age via the date stamp on the case. Inspect the battery hold-down and terminals for corrosion. Ask when the 12V battery was last replaced. Look here: Under bonnet — front right of engine bay adjacent to brake fluid reservoir