P1600 on Honda: How to Diagnose & Fix
Loss of Keep Alive Memory (KAM) Power
1 Honda model · 1 documented issue · 1 critical · $1,000-$3,000 repair
P1600 on Honda by model: symptoms, diagnosis and fix
The CR-Z uses Honda Integrated Motor Assist (IMA) system with a nickel-metal hydride (NiMH) battery pack located behind the rear seats. The battery pack degrades over time, losing capacity and causing the IMA system to become less effective at assisting acceleration and regenerating energy. The battery management system can also lose its calibration, causing incorrect state-of-charge readings and frequent IMA warning lights. In severe degradation, the IMA system shuts down entirely, leaving the car running on the 1.5L engine alone.
Common Symptoms
- IMA warning light illuminated on dashboard
- Check engine light with IMA-related codes
- Battery gauge showing low charge constantly
- Reduced power assist during acceleration
- Auto-stop feature no longer working
- Fuel economy significantly worse than rated
How to Fix
Perform a battery recalibration (deep discharge and full recharge cycle) using a Honda diagnostic tool. If recalibration does not resolve the issue, replace the IMA battery pack — Honda OEM replacements are available, and aftermarket rebuilt packs cost $1,000-2,000 less. Companies like Bumblebee Batteries offer refurbished IMA packs with warranties. After battery replacement, reset the battery module ECU and allow the system to relearn over 2-3 drive cycles.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
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Sources for this issue (1)
P1600 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 P1600 mean on a Honda?
P1600 stands for "Loss of Keep Alive Memory (KAM) Power." This manufacturer-specific code (common on Ford) means the engine computer lost its Keep Alive Memory (KAM) power, the constant battery feed that lets the PCM retain learned data such as fuel trims, idle, and transmission adaptive settings even when the key is off. An open circuit, weak battery, or recently disconnected battery can interrupt this feed and set the code. After it sets, the vehicle may idle or shift oddly until it relearns. It is usually a wiring, ground, or battery issue rather than a failed computer. On Honda it is documented across 1 model: CR-Z.
What are the most common causes of P1600?
The most common causes of P1600 are: Weak, discharged, or recently disconnected battery, Open or broken KAM power circuit wiring, Corroded or loose battery terminals or ground, Blown fuse feeding KAM power, Poor PCM connector contact, Faulty PCM (less common). The specific cause varies by vehicle.
How much does it cost to fix P1600 on a Honda?
Published repair estimates on Honda range from $1,000 to $3,000 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.
Looking for P1600 on a different make?
View P1600 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.