MajorCommonElectrical

Lexus RX: Hybrid battery ageing on RX400h and RX450h

Hybrid battery ageing on RX400h and RX450h is a common electrical fault on the Lexus RX on the 2005–2015 cars, and we rate it major. Putting it right costs ≈A$2,300 to ≈A$4,600 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 21 documented faults on the Lexus RX.

Vehicle: Lexus RX
Years: 2005–2015
Fuel: hybrid
System: Electrical

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

All Lexus RX faults21 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph for this fault yet. We would rather show none than show a picture of something else.

What goes wrong

RX400h (2005-2008) and RX450h (2009-2015) NiMH battery packs typically last 8-15 years in Australian conditions, and most of these cars are now at or beyond that window, so pack degradation and cell failures are increasingly common. The car still drives on a weak pack but economy collapses and the hybrid warning eventually appears. Australian specialists (Infinitev and others) supply reconditioned or new packs with warranty at a fraction of dealer cost.

What you would notice

Hybrid system warning light
Charge gauge swinging quickly full-to-empty
Fuel economy well above ~7 L/100km
Engine running constantly, weak EV mode

How to check it

Where to look. Traction battery under/behind the rear seats

Watch the energy monitor for rapid state-of-charge swings on the test drive.
Get a hybrid battery health check before purchase — specialists can read individual block voltages.
Check the battery cooling intake vents (rear seat area) aren't blocked with dust or pet hair.

What it costs to put right

≈A$2,300 to ≈A$4,600 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

“Has the hybrid battery been replaced or reconditioned, and by whom?”
“Can I see a recent hybrid health report?”

Now check the Lexus RX 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 the sources below. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them.

Edmunds RX400h hybrid battery failure forum thread

Lexus RX buyer questions

Is hybrid battery ageing on rx400h and rx450h serious on a Lexus RX?

We rate it major and common on the Lexus RX. RX400h (2005-2008) and RX450h (2009-2015) NiMH battery packs typically last 8-15 years in Australian conditions, and most of these cars are now at or beyond that window, so pack degradation and cell failures are increasingly common. The car still drives on a weak pack but economy collapses and the hybrid warning eventually appears. Australian specialists (Infinitev and others) supply reconditioned or new packs with warranty at a fraction of dealer cost.

How much does it cost to fix on a Lexus RX?

≈A$2,300 to ≈A$4,600 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 Lexus RX years are affected?

Our research records this fault on the 2005–2015 Lexus RX. 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?

Watch the energy monitor for rapid state-of-charge swings on the test drive. Get a hybrid battery health check before purchase — specialists can read individual block voltages. Check the battery cooling intake vents (rear seat area) aren't blocked with dust or pet hair. Look here: Traction battery under/behind the rear seats