Volvo Penta Exhaust Temperature Sensor 3862500 | Overheat Sender OEM

Volvo Penta Exhaust Temperature Sensor – 3862500

Part Information

• Part Number: 3862500
• Brand: Volvo Penta
• Official Product Type: Exhaust Temperature Sensor / Overheat Sender
• OEM Status: Genuine Volvo Penta
• Supersedes: 3861997
• System: Exhaust / Engine Monitoring – Exhaust Riser Overheat Detection
• Thread: 1/8-27 NPT
• Trigger Range: Approx. 239°F (115°C)
• Weight: Approx. 0.14 kg (0.3 lb)

What This Sensor Does

The 3862500 is the OEM exhaust temperature sensor installed in the exhaust riser or manifold area on selected Volvo Penta gasoline marine engines. Its job is to detect excessive exhaust temperature and trigger an overheat alarm when cooling-water flow through the exhaust system is lost or reduced — not to send temperature data to the engine’s dashboard gauge.

This is an important distinction: the 3862500 is an exhaust overheat sender, not the primary engine-coolant temperature gauge sender. It monitors a different part of the cooling circuit and serves as a safety warning device.

Compatible Applications

• Volvo Penta 3.0L (3.0GLM and related)
• Volvo Penta 4.3L V6 (4.3GL, 4.3GXi and related)
• Volvo Penta 5.0L V8 (5.0GXi, 5.0OSi and related)
• Volvo Penta 5.7L V8 (5.7GL, 5.7Gi, 5.7GXi and related)
• Volvo Penta 7.4L V8 (7.4Gi, 7.4GSi and related)
• Volvo Penta 8.1L V8 (8.1Gi and related)
• Volvo Penta 8.2L V8 (8.2GSi and related)

Confirm the exact engine model, serial number, and exhaust riser or manifold diagram before ordering. Many V6 and V8 applications use two sensors — one per exhaust side — while some inline-engine applications use one. Confirm quantity from your engine-specific parts diagram.

Quantity Note

Volvo Penta parts diagrams for selected 5.0L and 5.7L and other V6/V8 engines show two 3862500 sensors per assembly, one for each exhaust bank. Confirm the required quantity for your engine before ordering to ensure you have everything needed for the service.

Serial Number Fitment Notice

Use your engine model and serial number to locate the correct Volvo Penta intake/exhaust or electronic engine-control assembly diagram and confirm that 3862500 is specified at your sensor location before ordering.

When to Replace

• Exhaust-temperature alarm is active despite normal cooling-water flow
• Sensor does not trigger an alarm during confirmed exhaust overheating
• Electrical testing shows an open circuit or incorrect sender response
• Threaded body or terminal is corroded or physically damaged
• Wiring or connector damage has compromised the sensor circuit
• Sensor is damaged during exhaust manifold or riser service

A recurring exhaust overheat warning should also prompt inspection of the raw-water pump, impeller, hoses, manifolds, risers, and exhaust cooling passages — the sensor may be reporting a genuine cooling problem rather than failing itself.

Service Interval

No fixed replacement interval is published for this sensor. Inspect at each major service for corrosion on the threaded body and terminal. Replace immediately if an alarm fault is confirmed through electrical testing or if the sensor is disturbed during exhaust system service.

Installation Notes

Install the sensor in the correct exhaust-riser or manifold port specified in the applicable Volvo Penta diagram. Before installation, disconnect battery power, inspect the wiring harness and terminal, and confirm the threaded port is clean and undamaged. Use thread sealant only as required for your installation — some applications rely on the threaded body for electrical grounding, so excessive sealant on the threads can affect sensor operation. After installation, run the engine and verify normal cooling-water discharge from the exhaust and correct alarm-system operation.

Technical FAQ

Q: Is this the same as the engine coolant temperature sender for the dashboard gauge?
A: No. The 3862500 is the exhaust overheat sensor mounted in the exhaust riser or manifold area. It monitors exhaust temperature and triggers a safety alarm — it does not send a signal to the coolant temperature gauge on the helm.

Q: Does 3862500 replace 3861997?
A: Yes. Volvo Penta 3862500 is the current number and directly supersedes the earlier 3861997.

Q: How many sensors do I need?
A: Confirm from your engine’s parts diagram. Many V6 and V8 applications use two sensors (one per exhaust bank). Some inline engines use one. The diagram for your specific engine serial number is the most reliable reference.

Q: What thread size does this sensor use?
A: The aftermarket cross-reference specification lists 1/8-27 NPT. Confirm against your engine’s exhaust port specification before ordering.

Alternate Part Numbers

• Volvo Penta 3862500
• 3861997 (superseded)
• Sierra 18-7513
• Mallory 9-33850

Parts Desk Insights

The most common point of confusion with this sensor is customers thinking it is the primary engine coolant temperature gauge sender — it’s not. The 3862500 specifically monitors the exhaust riser area for overheating caused by lost or reduced cooling-water flow, and triggers an alarm rather than a gauge reading. If a customer’s exhaust overheat alarm is going off, the sensor should be tested electrically before replacing it — because a good sensor triggering a genuine overheat alarm means the cooling system needs attention, not the sensor. Also watch the quantity: V6 and V8 engines commonly need two, and ordering one when two are required means the job isn’t fully done.