P0A78 on Nissan: How to Diagnose & Fix
Drive Motor 'A' Inverter Performance
1 Nissan model · 1 documented issue · 1 critical · $1,500-$6,000 repair
P0A78 on Nissan by model: symptoms, diagnosis and fix
The 2011-2017 Leaf traction motor inverter can fail, resulting in complete loss of propulsion. The inverter converts DC battery power to AC for the motor. Symptoms include sudden power loss, error messages, and the vehicle going into turtle mode. This is a costly repair outside warranty.
Common Symptoms
- Sudden loss of power
- Turtle mode indicator
- Multiple warning lights on dash
- Vehicle won't accelerate
- EV system warning message
How to Fix
Diagnose with Nissan CONSULT to confirm inverter failure. Replace traction motor/inverter assembly. Cost: $3,000-6,000 at dealer. Used/refurbished inverters from salvage Leafs available for $1,500-2,500. Check if covered under the EV system warranty (5yr/60k miles); the 8yr/100k coverage applies to the lithium-ion battery only. 2014 Leafs built April 15-24, 2014 are covered by recall 14V263 (free inverter replacement).
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Nissan 2013-2017 LEAF power inverter 291A0-3NF0B
Confirm VIN, build and installed assembly.
- Genuine Nissan 2011-2012 LEAF traction motor and inverter drive unit 290J0-3NA1A
Confirm VIN, installed assembly, warranty, freight/core terms and non-returnability before purchase.
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Sources for this issue (3)
P0A78 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0A78 mean on a Nissan?
P0A78 stands for "Drive Motor 'A' Inverter Performance." P0A78 is a hybrid/electric-vehicle code indicating that the drive motor 'A' inverter is not performing as expected. The inverter converts the high-voltage battery's DC power into AC to drive the electric traction motor; when the control module sees abnormal inverter behaviour, such as phase current that does not follow the command, an internal switching or protection fault, or an inverter temperature problem, it sets this code and usually reduces or cuts power to protect the components. Symptoms include reduced power (limp mode), warning lights, or the vehicle refusing to drive. It points to the high-voltage drive inverter or its cooling rather than the gasoline engine. On Nissan it is documented across 1 model: Leaf.
What are the most common causes of P0A78?
The most common causes of P0A78 are: Internal inverter/power module fault (switching device or gate driver), Low coolant or air in the inverter cooling loop, Failed inverter/electronics coolant pump, Clogged or restricted inverter cooling passages/radiator, Faulty inverter temperature sensor, Inverter software/calibration fault, Related high-voltage system or motor fault. The specific cause varies by vehicle.
How much does it cost to fix P0A78 on a Nissan?
Published repair estimates on Nissan range from $1,500 to $6,000 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
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Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.