CriticalCommonElectrical

Lexus NX: NX300h hybrid inverter coolant pump failure

NX300h hybrid inverter coolant pump failure is a common electrical fault on the Lexus NX on the 2014–2021 cars, and we rate it critical. Putting it right costs $800 to $2,200 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 22 documented faults on the Lexus NX.

Vehicle: Lexus NX
Years: 2014–2021
Fuel: hybrid
Gearbox: cvt
System: Electrical

This page covers the Lexus NX 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 NX faults22 documented faults on this model

What you are looking at

No photograph available

We do not hold a verified photograph of the Water pump yet. We would rather show none than show a picture of a different part.

What goes wrong

The NX300h shares the 2AR-FXE hybrid drivetrain with the RAV4 Hybrid and ES300h. The electric inverter coolant pump (WICP) is a known failure point across Toyota/Lexus hybrid platforms of this era — the pump impeller degrades or the motor windings fail, causing inverter overheating. If the pump fails completely the hybrid system shuts down and the vehicle may be stranded. This is a recurring pattern flagged by NZ hybrid specialists servicing Toyota-platform vehicles.

What you would notice

Red triangle master warning light and hybrid system warning on dashboard
Reduced power or EV mode unavailable
Inverter overheating indicated by diagnostic codes P0A93 or P0A94
Absence of electric pump hum from under the bonnet when hybrid system is active

How to check it

Where to look. Hybrid inverter coolant circuit — electric pump mounted near the inverter under the bonnet

With the vehicle in Ready mode (not full ICE running), listen near the inverter coolant reservoir for the electric pump hum.
Check for any hybrid warning light history in the instrument cluster.
Scan for hybrid-related fault codes before purchase.

Parts involved: Water pump.

What it costs to put right

$800 to $2,200 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 warning triangle ever illuminated?”
“Has the hybrid inverter coolant pump ever been replaced?”
“Are there any stored fault codes from a recent OBD scan?”

Now check the Lexus NX 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 NX buyer questions

Is nx300h hybrid inverter coolant pump failure serious on a Lexus NX?

We rate it critical and common on the Lexus NX. The NX300h shares the 2AR-FXE hybrid drivetrain with the RAV4 Hybrid and ES300h. The electric inverter coolant pump (WICP) is a known failure point across Toyota/Lexus hybrid platforms of this era — the pump impeller degrades or the motor windings fail, causing inverter overheating. If the pump fails completely the hybrid system shuts down and the vehicle may be stranded. This is a recurring pattern flagged by NZ hybrid specialists servicing Toyota-platform vehicles.

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

$800 to $2,200 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 NX years are affected?

Our research records this fault on the 2014–2021 Lexus NX. 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?

With the vehicle in Ready mode (not full ICE running), listen near the inverter coolant reservoir for the electric pump hum. Check for any hybrid warning light history in the instrument cluster. Scan for hybrid-related fault codes before purchase. Look here: Hybrid inverter coolant circuit — electric pump mounted near the inverter under the bonnet