Accord Hybrid IMA light came on. Is it the hybrid battery or something cheaper?

Short answer: On an Accord Hybrid, IMA plus check engine lights with a battery deterioration code usually means the hybrid pack is wearing out. Rule out a weak 12-volt battery first, but owners found a new 12-volt only bought them a few weeks. One dealer quoted $5,400 for the pack. If the car shuts off while driving, get it scanned right away and check the 2005 fuel-pump recall.

Symptom: The IMA and check engine lights come on, the car feels weaker or gets worse mileage, or it dies and restarts.

What to check first

1. Run your VIN at nhtsa.gov/recalls (2005 fuse-box fuel-pump recall 05V132000 and the airbag recalls).
2. Load-test the 12-volt battery.
3. Get the full code list read with a Honda-capable scanner.
4. Make sure the vents that cool the pack (behind the rear seat) aren't blocked and the trunk isn't stuffed against them.
5. Compare a dealer pack quote with a hybrid battery shop.

Likely causes

1. Hybrid (IMA) battery losing capacity. The pack behind the rear seat wears out with age and miles. A battery deterioration code usually comes with the IMA light.
2. Weak 12-volt battery. A low 12-volt battery can set hybrid codes too. Dealers sometimes replace it first.
3. Pack overheating. The pack is cooled by air pulled from the cabin. Blocking the vents or packing the trunk tight can make it run hot.
4. Fuel pump losing power (2005 recall). A 2005 recall covers a loose terminal in the main fuse box that can cut power to the fuel pump so the engine won't start.

What it usually costs

One owner was quoted $5,400 by the dealer for a hybrid battery. Owners in these threads didn't post rebuilt-pack prices for the Accord.

Is it safe to keep driving?

Weak assist alone mostly means less power. A car that dies while driving is a crash risk; don't drive it on the highway until it's diagnosed.

DIY or shop?

The 12-volt battery and keeping the cooling vents clear are DIY. The hybrid pack is shop work. A hybrid's high-voltage system can stay live even with the car off. Leave the orange cables and the big battery to a hybrid-trained shop.

Recalls, bulletins and complaints in plain words

• Related recalls: NHTSA lists 05V132000 for some 2005 Accords: a loose terminal in the main fuse box can cut power to the fuel pump so the engine won't start. These years are also in Honda's Takata airbag recalls. NHTSA's recall lookup returned nothing under the separate name 'Accord Hybrid', so run your VIN. Check your VIN at nhtsa.gov/recalls. If your car is part of a recall, the dealer fixes it for free.
• Plain words: The complaint count below shows how often owners reported problems that mention these words to NHTSA. NHTSA's complaint lookup doesn't separate the hybrid from the regular model, so this count covers the whole model line. A count is not proof of a defect.
• NHTSA complaints: 329 keyword-matched complaints for Honda Accord (all versions) 2005–2007 (of 1644 unique complaints queried, NHTSA complaints API by model year, queried 2026-10-30; keywords: ima, hybrid, battery, loss of power) (NHTSA returned no data for 3 model-year queries). This counts complaints that mention these words. It is not a defect finding.

What owners report

• In Honda Accord Hybrid Battery Failure on Car Talk, a couple bought a 2006 Accord Hybrid with 123,000 miles, and two days later the IMA and check engine lights came on with a battery-pack deterioration code. They replaced the 12-volt battery because they'd read it could set that code, but the lights came back.
• In Honda Accord Hybrid IMA battery failure on Car Talk, an Accord Hybrid owner with 85,000 miles had the IMA and check engine lights come on. The dealer replaced the starter battery and it seemed fixed, but two months later the dealer said the hybrid battery was failing and quoted $5,400, with the part backordered.
• In Honda Accord Hybrid that dies on Car Talk, a 2005 Accord Hybrid would die now and then but always restart. The dealer blamed the IMA battery overheating because the trunk was packed full, and members were skeptical that was the whole story.

Quick tip

A new 12-volt battery is cheap and worth ruling out, but if the deterioration code comes back, the pack is the real problem. Get a second quote before paying dealer price on a car this old.

Vehicle focus: Honda Accord Hybrid (V6 IMA), 2005-2007.

Safety / mechanic note

Stalling and high-voltage parts are safety items. Verify with a mechanic.