Honda Start Button Failure (2016-2026): Fixing the 'Keyless Start System Problem'
A definitive guide to diagnosing and replacing the common failing push-button ignition switch in the Pilot, Accord, Civic, CR-V, HR-V, Passport, and Ridgeline.
- The most common failure symptom is the engine not starting on the first press, often with a 'Keyless Start System Problem' message and DTC B12C5.
- This ignition switch is plug-and-play and DOES NOT require dealer programming, making it an excellent DIY or independent shop repair.
- Honda issued a warranty extension (9 years/125k miles) for this issue on 2016-17 Pilots and 2017 Ridgelines (TSB 20-117).
- When buying a replacement, look for the updated part number 35881-TG7-A04, which is a direct, improved replacement for all previous versions.
The Common Honda Start Button Problem: TSB 20-117
A widespread issue affects the push-button ignition switch on many modern Honda vehicles, including the 2016-2025 Honda Pilot, 2023-2025 Honda Accord, 2022-2025 Honda Civic, 2023-2025 Honda CR-V, 2023-2025 Honda HR-V, 2019-2025 Honda Passport, and 2017-2026 Honda Ridgeline. The primary symptom is that the vehicle may not start on the first press of the button. Instead, it may require multiple presses to start, and a 'Keyless Start System Problem' or 'KEYLESS START SYSTEM ERROR' message will often appear on the instrument cluster.
This failure is so common that Honda issued Technical Service Bulletin (TSB) 20-117, which extended the warranty on the Engine Start/Stop switch for the 2016-2017 Pilot and 2017 Ridgeline to 9 years or 125,000 miles. Similar warranty extensions were issued for other models like the HR-V and Fit. The most common diagnostic trouble code (DTC) associated with this failure is B12C5 (Engine Start/Stop Switch Failure).
Symptoms of a Failing Ignition Switch
If your Honda's ignition switch is beginning to fail, you will likely experience one or more of the following symptoms:
- Vehicle Won't Start on First Press: This is the most common symptom. You press the button, the accessories may or may not turn on, but the engine does not crank. It may take two, three, or even more presses to get the vehicle to start.
- 'Keyless Start System Problem' Message: The multi-information display will show an error message, alerting you to a fault in the system. 🎬 Watch: 5 common causes for the Keyless Start System error message.
- Intermittent Starting: The problem may come and go. The car might start perfectly for a week and then fail to start multiple times in one day.
- Failure to Turn Off: In some cases, the switch can also fail to register a press to turn the vehicle off, requiring multiple attempts.
- DTC B12C5 Stored: A scan tool will reveal the trouble code B12C5, which points directly to a switch failure. 🎬 See how to diagnose and fix the B12C5 trouble code.
Pro Tip: If you are stranded and the button isn't working, try pressing it with the top of the key fob itself. In some cases, this can help the system recognize the fob and may allow the vehicle to start. Also, ensure your foot is firmly on the brake pedal, as a faulty brake pedal switch can produce similar no-start symptoms.
Is Programming Required? (The #1 Question)
No. This Engine Start/Stop switch does not need to be programmed, flashed, or coded to the vehicle. It is a simple plug-and-play component. The vehicle's anti-theft and immobilizer systems are managed by the key fob, the Body Control Module (BCM), and a separate keyless access control unit. The switch itself is just an input trigger. This makes replacement straightforward for DIY mechanics and means a used switch from a compatible vehicle will function correctly without a trip to the dealer.
Buying a Used Ignition Switch
Purchasing a used OEM ignition switch is a smart way to save money, as the part is simple, reliable (especially later revisions), and does not require programming. Here’s what to look for:
- Verify the Part Number: The best choice is the latest revised part, 35881-TG7-A04. This version replaces all prior versions (including A01, A02, A03, 701, 702, 703) and presumably has an improved internal design. When buying used, aim for this part number if possible.
- Physical Inspection: Check for any signs of damage to the plastic housing or the electrical connector pins. The button should depress and return smoothly with a tactile click. Avoid any switches that look like they have been exposed to liquid spills.
- Source Vehicle: A switch from a lower-mileage, later-model-year vehicle is always preferable. Since the failure is related to wear and tear from use, lower mileage means more life left in the switch.
- Why Used OEM is a Good Choice: For a simple electronic part like this, a genuine used OEM switch is often superior to a cheap new aftermarket part. The plastics, contacts, and illumination will match your vehicle's interior perfectly, and you get a factory-quality part that has been proven to work.
Warning: This is a push-button ignition switch for gasoline models only. It will not work with hybrid vehicles, which use a different power-up sequence and switch. It is also only for vehicles equipped with a keyless start system and will not work on models that use a traditional metal ignition key.
Replacement Overview (DIY)
Replacing the ignition switch is a feasible DIY job that typically takes under an hour and requires basic tools.
- Disconnect the Battery: As a safety precaution, disconnect the negative terminal of your 12V battery.
- Remove Trim Panels: You will need to remove the plastic trim panels around the steering column and/or center dash area to gain access to the back of the switch. These are usually held in with clips and a few screws. A plastic trim removal tool is highly recommended to avoid scratching the panels.
- Unplug and Remove the Switch: The switch is typically held in place by plastic tabs. Squeeze the tabs, disconnect the single electrical connector, and push the switch out from the front of the panel.
- Install the New Switch: Installation is the reverse of removal. Push the new switch into the panel until it clicks, reconnect the electrical harness, and reassemble the dash trim. 🎬 Watch this step-by-step guide to replacing the Pilot's ignition switch.
Cost to Replace the Ignition Switch
| Item | Estimated Cost | Notes |
|---|---|---|
| New OEM Part | $90 - $135 | Purchased from a Honda dealership parts counter. |
| New Aftermarket Part | $25 - $75 | Prices vary by brand and quality. |
| Used OEM Part | $20 - $60 | A cost-effective option, especially for the updated 'A04' version. |
| Shop Labor | $75 - $150 | The job takes less than an hour (TSB flat rate is 0.3 hours), so expect to be charged for one hour of labor. |
OEM Part Numbers and Supersessions
The following part numbers are known to be associated with this switch. The latest part number, 35881-TG7-A04, is the recommended replacement.
- 35881-TG7-A04 (Latest Version)
- 35881-TG7-A03 (Superseded)
- 35881-TG7-A02 (Superseded)
- 35881-TG7-A01 (Superseded)
- 35881-TG7-703 (Superseded)
- 35881-TG7-702 (Superseded)
- 35881-TG7-701 (Superseded)
- 35881-TZAA01
Source: Honda parts catalogs.
Frequently Asked Questions (FAQ)
Do I need to take my car to the dealer to replace this switch?
No. Because this switch does not require any programming, it can be replaced by an independent mechanic or as a DIY project. A dealer visit is not necessary unless the repair is being performed under the warranty extension.
Is a failing start button dangerous?
While it is very frustrating, the common failure mode of this switch is not typically dangerous. It usually prevents the car from starting, but does not cause it to stall while driving. However, any issue with the ignition system should be addressed promptly to avoid being stranded.
Could my problem just be the key fob battery?
Yes, a weak key fob battery can cause similar issues. Before replacing the switch, try replacing the battery in your key fob. If the car still has trouble starting and you see the 'Keyless Start System Problem' message, the ignition switch is the more likely culprit.
Will a used ignition switch work?
Yes, a used OEM switch from a compatible vehicle will work perfectly and is a great way to save money. Since no programming is required, it is a simple plug-and-play replacement. Try to find the latest part number (35881-TG7-A04) from a low-mileage vehicle.
Helpful Videos
Technical Specifications
OEM Part Numbers: 35881-TG7-A04 35881-TG7-A03 35881-TG7-A02 35881-TG7-A01 35881-TG7-703 35881-TG7-702 35881-TG7-701 35881-TZAA01
Push-button switch for keyless start systems. Single electrical connector. No programming required.
We Have This Part in Stock
The information in this article is provided for general reference and educational purposes only. Vehicle specifications, procedures, and part compatibility can vary by production date, trim level, and region. Always consult your vehicle's factory service manual and verify part numbers before purchasing or performing repairs. Safety-critical components such as airbags, seat belts, and braking systems should be installed by a qualified professional.
- Honda Pilot:
- Honda Accord:
- Honda Civic:
- Honda CR-V:
- Honda HR-V:
- Honda Passport:
- Honda Ridgeline:
- 🎬 Helpful Videos
- 🛍️ Shop This Part
- The Common Honda Start Button Problem: TSB 20-117
- Symptoms of a Failing Ignition Switch
- Is Programming Required? (The #1 Question)
- Buying a Used Ignition Switch
- Replacement Overview (DIY)
- Cost to Replace the Ignition Switch
- OEM Part Numbers and Supersessions
- Frequently Asked Questions (FAQ)
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