Arco IG001 Ignition Sensor — MerCruiser Thunderbolt IV & V GM V6 / V8
Free returns on all eligible orders
You have 30 days to request a return. All sale items are final sale.
OEM-Grade Ignition Sensor for MerCruiser Thunderbolt IV & V Systems
The Arco IG001 is a direct-fit replacement ignition sensor (trigger module) engineered for MerCruiser GM V6 and V8 inboard and sterndrive engines equipped with Thunderbolt IV or Thunderbolt V ignition systems. This sensor controls spark timing signals within the distributor and is a critical component for reliable engine starting and smooth operation.
Compatible Applications
- MerCruiser GM V6 engines — Thunderbolt IV ignition
- MerCruiser GM V6 engines — Thunderbolt V ignition
- MerCruiser GM V8 engines — Thunderbolt IV ignition
- MerCruiser GM V8 engines — Thunderbolt V ignition
Replaces OEM Part Numbers
- MerCruiser: 87-892150Q02, 892150A02, 861780A2, 91019A6, 861780Q4, 861780A4, 91019A3, 91019A2
- Sierra: 18-5116-1
Parts Desk Insights
The IG001 is the right part when a Thunderbolt IV or V engine cranks but won’t fire, or exhibits intermittent no-spark conditions — classic signs of a failed ignition sensor. It’s one of the more common failure points on aging Thunderbolt systems and is often overlooked during basic tune-ups. When replacing the sensor, it’s good practice to service the full distributor at the same time — pair with the Arco DR004 Distributor Rotor for a complete Thunderbolt ignition refresh. If you’re unsure which sensor fits your engine, compare with the Arco IG005 Ignition Sensor, which covers a different Thunderbolt application range.
Shipping information
In-stock and OEM parts: ship same or next business day.
Locally warehoused items: ship within 1-3 business days.
Special-order items: timeline confirmed after order.
Returns & warranty
Returns & Satisfaction Guarantee
We stand firmly behind the quality of every product we sell. Your confidence matters to us — and we back it with a straightforward 30-Day Satisfaction Guarantee.
If you are not fully satisfied, you may request a return within 30 days of delivery. All returns must receive pre-approval prior to being sent back. Unauthorized returns will not be accepted.
To qualify for a return:
Item must be in new, unused condition
Product must be in its original packaging
All parts, components, hardware, manuals, and accessories must be included
Packaging must be undamaged and suitable for resale
Important:
Electronics are strictly inspected. No returns on open-box electronics. Exceptions may apply only with prior written approval. Any electronic unit that has been installed, powered, activated, or altered may not be eligible for return.
We are serious about product integrity — and equally serious about taking care of our customers. If there is ever a product issue, contact us immediately so we can make it right.
For return authorization, please contact our support team before shipping anything back.