My 2022 Nissan Leaf developed a serious HV battery fault. Nissan diagnosed an internal fault in the battery — then refused full cover because of mileage.

1. What Happened

In February 2022, I purchased a brand-new Nissan Leaf from Nissan Fermoy in Cork. It was a 40 kWh model — the SV Premium. I chose Nissan because they were one of the pioneers of electric vehicles. The Leaf had a reputation. The dealer was local, part of the official Nissan network, and I assumed that meant proper expertise and aftercare.

The car was financed through a hire purchase agreement with AIB Finance & Leasing. It was a significant investment for my family.

In late November 2025 — approximately one week after the most recent service at 106,894 km — the car developed a severe and undeniable fault. Sudden loss of state-of-charge under load, turtle mode, loss of propulsion. It became dangerous.

2. Nissan's Own Diagnosis

I brought the car to Nissan Fermoy. On the first visit (8 December 2025), they performed a static test. Nothing conclusive was found. The battery appeared broadly healthy at rest.

On the second visit (17 December 2025), they performed a road test under load using Nissan's own CONSULT III Plus diagnostic equipment. This time, the data told the story clearly:

• Most cells: approximately 3,300–3,350 mV under load
• One cell/module: dropped to approximately 2,950 mV
• A ~300 mV delta — far beyond normal variation

Evidence: diagnostic data The data was forwarded to Nissan Tech Line. Their conclusion, as recorded on the dealer's own service invoice dated 18 February 2026:

"Charge dropping while driving checked and confirmed. Carry out main battery test on road under load and under normal driving. Recorded all data under txt format and forward to Nissan Tech Line. Nissan Tech Line advised internal fault in HV battery."

This is not my interpretation. This is Nissan's own diagnosis, in their own words, on their own invoice.

3. Nissan's Response: Out of Warranty

Having confirmed the fault — using their own equipment, verified by their own Tech Line — Nissan's position was simple: out of warranty.

Their reasoning: the Electric Vehicle System warranty covers defects for 5 years or 100,000 km. My odometer showed 108,484 km at the time of diagnosis. Therefore, in their view, no warranty coverage.

They offered what they called "goodwill" — Nissan would contribute 50% of the battery cost. The remaining cost to me: approximately €8,000–€8,500 including labour and transport to their specialist centre in Naas.

Evidence: dealer correspondence I sent a formal complaint raising my statutory consumer rights. The response from the Dealer Principal addressed only the warranty position. It did not engage with statutory rights. It did not answer whether the vehicle is safe to drive. It stated:

"This is the only process Nissan will accept, and it is the only way for your case to be considered."

4. What Nissan Has Not Answered

These are the questions I believe Nissan Ireland, Nissan Fermoy, and Nissan Tech Line should answer publicly or directly:

1. Why was no battery load test or cell-level diagnostic recorded during six Nissan dealer service visits?
2. Is the vehicle safe to drive with a confirmed internal HV battery fault?
3. Why is the mileage at diagnosis being treated as decisive if symptoms may have existed earlier?
4. What exact diagnostic data did Nissan Tech Line review before advising that there was an internal fault in the HV battery?
5. Will Nissan provide the full CONSULT III+ diagnostic report, including DTCs, Time fields and Freeze Frame Data?
6. Why was full battery replacement proposed rather than a module-level assessment or repair?
7. Why did the dealer response address only the manufacturer warranty and not statutory consumer-rights concerns?
8. Why did Nissan offer a 50% goodwill contribution but refuse to stand over the full repair?
9. Why should Irish consumers trust Nissan's EV dealer network if serious battery faults require escalation to a specialist centre and are not proactively tested during routine servicing?

5. Three Years of Servicing — No Battery Diagnostics

I did everything right. I brought the car back to Nissan Fermoy for every service, on schedule, without exception. Over three and a half years, the car was serviced six times at the same dealership.

Not once — across any of those six service visits — was a battery cell-level diagnostic recorded. The service invoices consistently show items like "checked for fault codes", "plugged in for faults and updates all OK", brakes, tyres, suspension, pollen filters. Routine work. But never a battery health check under load.

For an electric vehicle, the battery is not an optional component. It is the core system. A routine static fault-code check is not the same as testing the battery under load. In my case, the static check did not identify the issue; the fault was confirmed only when Nissan road-tested the car under load.

6. A Known Wider Pattern

The 40 kWh Nissan Leaf battery has a documented wider failure pattern. Similar technical failure modes are recorded in official recall filings.

The U.S. National Highway Traffic Safety Administration (NHTSA) has issued recalls for 2019–2022 Nissan Leafs describing battery cells that develop excessive lithium deposits, increasing electrical resistance and causing state-of-charge fluctuation. The specific recalls are:

• NHTSA Recall 25V655 / Nissan R25C8 — certain 2021–2022 Nissan LEAF vehicles. The filing describes excessive lithium deposits within battery cells, increased electrical resistance, and potential state-of-charge fluctuation. It also states there is no preceding warning to the customer.
• NHTSA Recall 24V-700 / Nissan R24B2 — related earlier filing for certain 2019–2020 Nissan LEAF vehicles. The filing uses the same technical explanation: excessive lithium deposits, increased electrical resistance, and potential state-of-charge fluctuation.

Public owner reports describe similar symptoms, but the strongest documented support for this section is the official NHTSA recall language: excessive lithium deposits, increased electrical resistance, and state-of-charge fluctuation.

7. Early Signs I Didn't Understand

Owner recollection Looking back, I believe I noticed early symptoms before the car reached 100,000 km. For months, I experienced a brief, repeatable dip in power at the same point on a hill near my home. At the time, it presented as a momentary hesitation and I did not recognise it as a battery fault.

It was only after the severe failures began in late November 2025 that I made the connection. In hindsight, this was consistent with the early stages of the weak-cell voltage-sag problem — the very defect pattern documented in the NHTSA recalls.

I am seeking the car's diagnostic records to establish whether any internal fault data was recorded before the 100,000 km threshold.

Opinion In my opinion, if a battery load test had been performed at any of my earlier service visits — when this symptom was already present but subtle — the defect could have been identified while the car was still within the warranty mileage threshold.

8. When It Became Dangerous

In late November 2025 — approximately one week after the most recent service at 106,894 km — the fault became severe and undeniable.

9. Why This Matters for Nissan EV Buyers in Ireland

During one of my visits to the dealership, I was told directly by a staff member — in the context of explaining what they could and couldn't do — words to the effect of:

"When it comes to brakes and shocks we're grand, but anything to do with the system we have to send it up to Naas."

Opinion In my opinion, this raises a serious question: if EV-specific diagnosis and repair must be escalated to a specialist centre in Naas, why was a battery load or cell-level issue not proactively checked during years of routine servicing?

So the situation, as I experienced it, was:

• A car with symptoms matching a documented wider battery failure pattern
• A dealer who serviced it 6 times but never ran a battery diagnostic
• A dealer who, by their own statement, must escalate EV system work to Naas
• A defect that I believe was likely present — causing subtle symptoms — before the warranty mileage limit
• A warranty refusal based on mileage at the point of diagnosis, not the point the defect began

10. Why I Believe Nissan's EV Support Is Not Fit for Purpose

Opinion Based on my documented experience, I do not believe Nissan's EV aftersales support was fit for purpose in this case.

The official Nissan dealer sold me the car. The same dealer serviced it for years. Across six service visits, no battery load test or cell-level diagnostic was recorded. A static check did not identify the issue. The fault was confirmed only when Nissan road-tested the car under load and sent the data to Nissan Tech Line.

Nissan's own paperwork then recorded the conclusion: "Nissan Tech Line advised internal fault in HV battery."

Despite that, Nissan treated the issue as a mileage-limit warranty problem, offered only a 50% goodwill contribution, and did not answer key questions about safety, statutory rights, or the diagnostic records behind the decision.

If You Own a Nissan Leaf 40 kWh, Do This Now

Actions Taken

This section will be updated as the case progresses.

My Request to Nissan Ireland

I am asking Nissan Ireland to stand over this vehicle by doing the following:

1. Repair or replace the defective HV battery at no cost to me.
2. Refund the diagnostic costs incurred in confirming the fault.
3. Provide the full CONSULT III+ diagnostic report, including all DTCs, Time fields and Freeze Frame Data.
4. Provide the Nissan Tech Line records and the data reviewed before concluding there was an internal fault in the HV battery.
5. Explain why a serious internal HV battery fault on a 2022 electric vehicle is being treated only as a mileage-limit warranty issue.
6. Confirm in writing whether the vehicle is safe to drive in its current condition.
7. Explain why no battery load test or cell-level diagnostic was recorded during six Nissan dealer services before the confirmed HV battery fault.