3075269 | Genuine Cummins® Onan SWITCH

1. Compatible Engine Families

This legacy component is primarily engineered for older, legendary Onan twin-cylinder, air-cooled engines that are widely regarded for their bulletproof reliability. It explicitly fits equipment powered by:

• Onan CCK & CCKA series engines

• Onan CCKB & CCKM series engines

2. Industry Applications & Equipment Types

Because these robust vintage engines were heavily used across multiple heavy-duty sectors before modern electrical systems took over, this switch fits:

• Vintage RV & Mobile Generators: Installed in classic motorhomes (from the 1970s through the 1990s) utilizing onboard Onan power plants to handle interior AC loads.

• Industrial Engine-Driven Welders: Found on legacy commercial welding machines (like older Miller or Lincoln welders that used Onan CCK/CCKA engines as their standalone power sources).

• Utility & Agricultural Machinery: Antique tractors, industrial pumps, and specialty heavy equipment attachments that rely on original Onan internal combustion designs.

1. What is it?

Depending on the specific engine catalog layout, this component is technically designated as an Engine Intake Manifold Temperature Sensor or a specialized Thermal Switch. It is built with a heavy-duty, heat-tolerant sensing tip and a ruggedized electrical connector housing designed to survive the severe, non-stop vibrations of an active generator compartment.

2. Core Functions

• Manifold Temperature Monitoring: It continuously reads the temperature of the air passing through the intake manifold before it enters the engine cylinders.

• Combustion Optimization: By relaying accurate, real-time temperature data to the Engine Control Unit (ECU), it allows the vehicle's computer to calculate the optimal air-fuel ratio and adjust injector timing for efficient, stable combustion.

• Overheating Protection: If internal manifold temperatures spike dangerously high, the switch acts as a safety sensor, communicating the fault to the system to reduce engine output or trigger an emergency shutdown to prevent melting internal components.

1. Rough Running and Misfires at Startup

If the sensor fails or reports an incorrect temperature, the engine block may struggle to calculate the correct amount of fuel required for a cold start. This results in rough idling, engine spitting, or stumbling right after starting up until the engine warms up.

2. Black Smoke from the Exhaust (Rich Fuel Mixture)

If the switch fails dynamically and gets stuck sending a "permanently freezing cold" temperature reading to the computer, the ECU will continuously dump excessive amounts of diesel fuel into the cylinders. This unburnt fuel leads to heavy black exhaust smoke and poor fuel economy.

3. Hesitation and Sluggish Engine Response

Under acceleration or varying generator loads, the air density changes rapidly inside the manifold. A lagging, contaminated, or shorted switch cannot adjust its resistance values fast enough, causing the engine to bog down, hesitate, or feel significantly down on power.

4. Hard Starting in Extreme Weather

A dead sensor cannot help the engine recognize freezing outdoor temperatures. Without this reading, the computer will fail to activate the optimal fuel enrichment or adjust the timing properly, leading to extended cranking periods in cold winter conditions.

5. "Check Engine" Codes / Malfunction Lights

The vehicle's onboarding diagnostic system monitors the voltage loop of this switch constantly. Common diagnostic codes indicating a failing sensor include:

• P0112: Intake Air Temperature Sensor 1 Circuit Low

• P0113: Intake Air Temperature Sensor 1 Circuit High