MajorCommonElectrical

Lexus IS: IS 300h Hybrid Traction Battery (NiMH) Capacity Degradation

IS 300h Hybrid Traction Battery (NiMH) Capacity Degradation is a common electrical fault on the Lexus IS on the 2013 onward cars, and we rate it major. Putting it right costs $3,500 to $9,000 at New Zealand independent workshop rates. 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 41 documented faults on the Lexus IS.

Vehicle: Lexus IS
Years: 2013 onward
Fuel: hybrid
Gearbox: cvt
System: Electrical

This page covers the Lexus IS 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 IS faults41 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

The IS 300h hybrid uses a sealed nickel-metal hydride (NiMH) high-voltage traction battery pack whose usable capacity declines progressively with age and charge cycles. As individual cells degrade and balance drifts, the hybrid management system narrows the usable state-of-charge window, reducing effective pack capacity. This forces the petrol engine to engage at lower speeds and more frequently, increasing fuel consumption significantly, and in advanced cases the hybrid system triggers a master warning and may limit total vehicle power output.

What you would notice

Reduced or absent EV-mode operation — engine fires immediately at low urban speeds
Significantly higher fuel consumption than the rated 4.7–5.0L/100km figure
Hybrid system or high-voltage battery warning light illuminating
Battery charge and discharge gauge cycling more rapidly than normal during normal driving
READY indicator slower than normal to illuminate after pressing the start button

How to check it

Where to look. Boot floor beneath luggage area trim panel, or beneath rear seat depending on market specification

Prius app or equivalent) to read individual cell block voltages and state of health percentage. On the test drive note whether the car will run in EV-only mode at low urban speeds — a degraded pack forces the engine on immediately. Compare actual real-world fuel consumption against the 4.7L/100km rated figure. Request any hybrid system service history. If a workshop inspection is possible: Use an OBD-II scanner with hybrid battery monitoring capability (Dr.

What it costs to put right

$3,500 to $9,000 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, 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 traction battery ever been tested, reconditioned, or replaced?”
“What real-world fuel consumption are you currently achieving in daily driving?”
“Has any hybrid system warning light or high-voltage battery warning appeared?”

Now check the Lexus IS 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 has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

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.

Lexus IS buyer questions

Is is 300h hybrid traction battery (nimh) capacity degradation serious on a Lexus IS?

We rate it major and common on the Lexus IS. The IS 300h hybrid uses a sealed nickel-metal hydride (NiMH) high-voltage traction battery pack whose usable capacity declines progressively with age and charge cycles. As individual cells degrade and balance drifts, the hybrid management system narrows the usable state-of-charge window, reducing effective pack capacity. This forces the petrol engine to engage at lower speeds and more frequently, increasing fuel consumption significantly, and in advanced cases the hybrid system triggers a master warning and may limit total vehicle power output.

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

$3,500 to $9,000 at New Zealand independent workshop rates. 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 IS years are affected?

Our research records this fault on the 2013 onward Lexus IS. 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.