2017 Honda Clarity Problems: 3 Issues Every Owner Should Know

2017 Honda Clarity Problems: 3 Issues Every Owner Should Know | Au7o

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180 owners

On the 2017-2021 Honda Clarity 1.5L Atkinson, the Honda Clarity PHEV can experience a dangerous loss of power when transitioning from electric to gasoline engine operation, particularly under high-load conditions such as highway hills, cold weather, or when the battery is nearly depleted. The vehicle may drop from highway speed (60+ mph) to as low as 20 mph while the engine revs loudly but fails to deliver power, behaving as if the transmission is in neutral. The 1.5L Atkinson-cycle engine struggles to maintain speed when the electric motor assistance diminishes, and the power management software does not always transition smoothly between operating modes.

This issue also affects: Volkswagen Passat, Mercedes-Benz C-Class, MINI GP

Common Symptoms

Vehicle drops from highway speed to 20-30 mph unexpectedly
Engine revs loudly but vehicle does not accelerate
Power System Problem warning on dashboard
Gear icon with exclamation mark appears
Issue worsens in cold weather or on steep grades

How to Fix

Visit a Honda dealer for the latest PCM software update, which improves the hybrid-to-gas transition logic. Keep the battery charged above 2 bars when highway driving in cold weather. In HV mode on long highway grades, manually press the HV Charge button to maintain battery reserve for power blending. If power loss occurs, safely pull over, turn off the vehicle for 60 seconds, then restart — this resets the power management system. The issue is less severe after the 2019 software updates.

What Owners Are Using

Parts and tips from 180+ owners who fixed this issue

TipOn highway trips longer than your EV range, use HV mode from the start rather than draining the battery completely. Keeping 20-30% battery charge allows the electric motor to supplement the gas engine on hills, preventing the power loss scenario entirely.
TipIf you experience frequent power loss on your commute, ask the dealer specifically for TSB 19-056 and TSB 20-008 software updates. Not all dealers proactively apply these unless you request them.
UpgradeBluetooth OBD-II scanner for reading engine codes and monitoring live data (BlueDriver Bluetooth OBD2 Diagnostic Scan Tool)
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UpgradeQuality synthetic oil and filter combo for engine maintenance (Mobil 1 Full Synthetic Oil and Filter Bundle)
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Typical repair cost:$0 - $150

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Community Reported

High Confidence180 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

145 owners

On the 2017-2021 Honda Clarity, the Honda Clarity PHEV may fail to start charging when plugged in, or may stop charging before the high-voltage lithium-ion battery reaches full capacity. The onboard charger or charging control software may not properly communicate with the EVSE (charging station), resulting in no charging activity despite the plug being connected and the charge indicator light not illuminating. Some owners also report the battery only charging to partial capacity (6-36 miles range instead of the expected 47 miles), which may indicate battery degradation or a software calibration error in the battery management system.

Common Symptoms

Charge indicator light does not illuminate after plugging in
Charging starts but stops after a few minutes
EV range significantly lower than expected after full charge
Ready to Charge notification never appears on the dash
Charging timer shows unreasonably long charge times

How to Fix

Try unplugging and re-plugging the charge connector firmly — a loose connection is the most common cause. If charging still fails, reset the vehicle by turning off, locking with the key fob, waiting 5 minutes, then plugging in again. Visit a Honda dealer for the charging system software update (TSB addresses EVSE communication). For range degradation, the dealer can run a battery health check — if capacity is below 66%, the battery may be eligible for warranty replacement under the 10-year/150,000-mile hybrid battery warranty.

What Owners Are Using

Parts and tips from 145+ owners who fixed this issue

TipBefore assuming the charger is broken, test with a different Level 2 EVSE if possible. The Clarity can be picky about some aftermarket chargers. The OEM Honda charge cord and ChargePoint stations have the highest compatibility.
UpgradeHigh-performance AGM battery with excellent cold cranking amps and deep cycle capability (Optima RedTop AGM Battery)
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UpgradeOEM-quality replacement battery with reliable performance (ACDelco Professional AGM Battery)
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UpgradeAutomatic battery maintainer to prevent parasitic drain issues during storage (Battery Tender Junior 12V Battery Charger Maintainer)
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UpgradePremium electrical tape for wiring repairs and harness wrapping (3M Super 33+ Vinyl Electrical Tape)
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UpgradeSplit wire loom tubing to protect repaired or exposed wiring harnesses (DEI Split Wire Loom Tubing)
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UpgradeWeatherproof terminal connector kit for reliable wiring repairs (Molex Automotive Terminal Connector Kit)
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UpgradeLevel 2 portable EV charger for reliable home or on-the-go charging (Lectron Portable Level 2 EV Charger)
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Typical repair cost:$0 - $300

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145+ owners have reported this issue

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Community Reported

High Confidence145 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Community Reported

210 owners

On the 2017-2021 Honda Clarity, the Honda Clarity PHEV and EV models experience 12V auxiliary battery drain when the vehicle is not driven for extended periods (7-14 days). Unlike conventional vehicles, the Clarity's 12V battery is relatively small and powers multiple always-on systems including the telematics module, keyless entry receiver, and battery management system monitoring. The 12V battery does not charge from the high-voltage battery when the vehicle is off, leading to a dead 12V battery that prevents the vehicle from powering on even if the main traction battery is fully charged.

Common Symptoms

Vehicle will not power on after sitting for a week or more
Dashboard completely dark when pressing the start button
Key fob does not unlock doors remotely
Clock and radio presets reset after jump-starting
Charging will not initiate even when plugged in

How to Fix

If the vehicle will sit unused for more than a week, connect a 12V battery tender or maintainer ($25-$40). The 12V battery is located in the trunk area. If the 12V battery dies, use a jump starter or jumper cables on the 12V battery terminals under the hood to boot the vehicle, then let it run for 30 minutes to recharge. Replace the 12V battery with a high-quality AGM battery every 3-4 years proactively ($150-$250). Consider unplugging the OBD-II port if you have an aftermarket dongle connected, as these draw parasitic current.

What Owners Are Using

Parts and tips from 210+ owners who fixed this issue

TipA NOCO Genius1 or Battery Tender Junior ($25-$35) connected to the 12V battery when the car sits for extended periods completely eliminates this issue. Run the cable through the trunk seal — it compresses enough to close without damage.
UpgradeHigh-performance AGM battery with excellent cold cranking amps and deep cycle capability (Optima RedTop AGM Battery)
View on Amazon
UpgradeOEM-quality replacement battery with reliable performance (ACDelco Professional AGM Battery)
View on Amazon
UpgradeAutomatic battery maintainer to prevent parasitic drain issues during storage (Battery Tender Junior 12V Battery Charger Maintainer)
View on Amazon
UpgradeOEM-quality starter motor for reliable engine cranking (Denso Starter Motor)
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UpgradeRemanufactured starter with gear reduction for improved cranking performance (Remy Remanufactured Starter Motor)
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UpgradeAutomotive relay replacement set for common relay failures (Bosch Automotive Relay 5-Pin 12V)
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UpgradeDigital multimeter for diagnosing fuse, relay, and module electrical faults (Innova Digital Multimeter)
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Typical repair cost:$25 - $250

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210+ owners have reported this issue

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Community Reported

High Confidence210 reportsLast reported by owners Mar 2026Reviewed Mar 2026

Frequently Asked Questions

What are the most common Honda Clarity problems?

According to Au7o's analysis of 535+ owner reports, the 2017-2017 Honda Clarity has 3 documented issues. The most frequently reported are: Sudden Power Loss and Engine Over-Rev on Highway, Intermittent Charging Failure and Battery Not Fully Charging, 12V Auxiliary Battery Drain When Vehicle Sits Idle. Of these, 1 is rated critical and should be addressed promptly.

Is the Honda Clarity reliable?

The 2017-2017 Honda Clarity has 3 known issues documented across 535+ owner reports. 1 issue is rated critical: Sudden Power Loss and Engine Over-Rev on Highway. Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Honda Clarity problems?

Repair costs for known Honda Clarity issues range from $0 to $300, depending on the specific problem and whether you choose DIY or professional repair. The most critical issue, Sudden Power Loss and Engine Over-Rev on Highway, typically costs $0-$150 to repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2017-2021 Honda Clarity Sudden Power Loss and Engine Over-Rev on Highway?

The Honda Clarity PHEV can experience a dangerous loss of power when transitioning from electric to gasoline engine operation, particularly under high-load conditions such as highway hills, cold weather, or when the battery is nearly depleted. The vehicle may drop from highway sp… Repairs typically run $0-$150. Severity: high.

What is the 2017-2021 Honda Clarity Intermittent Charging Failure and Battery Not Fully Charging?

The Honda Clarity PHEV may fail to start charging when plugged in, or may stop charging before the high-voltage lithium-ion battery reaches full capacity. The onboard charger or charging control software may not properly communicate with the EVSE (charging station), resulting in… Repairs typically run $0-$300. Severity: medium.

What is the 2017-2021 Honda Clarity 12V Auxiliary Battery Drain When Vehicle Sits Idle?

The Honda Clarity PHEV and EV models experience 12V auxiliary battery drain when the vehicle is not driven for extended periods (7-14 days). Unlike conventional vehicles, the Clarity's 12V battery is relatively small and powers multiple always-on systems including the telematics… Repairs typically run $25-$250. Severity: low.

2017 Honda Clarity Problems: 3 Issues Every Owner Should Know

All 3 Known Issues

2017-2021 Honda Clarity: Sudden Power Loss and Engine Over-Rev on Highway#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2017-2021 Honda Clarity: Intermittent Charging Failure and Battery Not Fully Charging#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

2017-2021 Honda Clarity: 12V Auxiliary Battery Drain When Vehicle Sits Idle#

Common Symptoms

How to Fix

What Owners Are Using

Research This Issue

Other Honda Models

Frequently Asked Questions

What are the most common Honda Clarity problems?

Is the Honda Clarity reliable?

How much does it cost to fix common Honda Clarity problems?

What is the 2017-2021 Honda Clarity Sudden Power Loss and Engine Over-Rev on Highway?

What is the 2017-2021 Honda Clarity Intermittent Charging Failure and Battery Not Fully Charging?

What is the 2017-2021 Honda Clarity 12V Auxiliary Battery Drain When Vehicle Sits Idle?