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SPN 1491moderate severity✨ AI-generated

Engine Shutdown Switch

Indicates an issue with the engine shutdown switch.

Heads up: this code wasn't in our hand-written library yet, so DiagCoach AI built this page on the fly. Double-check critical specs against service info before condemning parts.

What it means (plain English)

The engine shutdown switch is supposed to stop the engine if it detects a problem. When it registers a fault, it means it’s either not working correctly or there's a wiring issue preventing it from doing its job.

What the computer is actually seeing

The computer sees a signal from the engine shutdown switch that's either consistently off when it should be on, or there's a voltage reading that doesn't match expected ranges.

What a healthy reading looks like

The shutdown switch should show a voltage of approximately 0V (off) or around 5V (on) when activated. Conditions should evaluate within a tolerance of 0.5V.

Guided diagnostic — the DiagCoach way

Don't just throw parts at it. Walk through these in order — each step tells you whether to keep going or stop and fix what you found.

  1. 11. Inspect wiring and connectors at the engine shutdown switch for damage or corrosion. Decision: If damaged, repair or replace.
  2. 22. Check the engine shutdown switch with a multimeter. When the switch is activated, you should see a change from 0V to around 5V. Decision: If no change, replace the switch.
  3. 33. Verify the control module is receiving the expected voltage on its input pin for the shutdown switch. It should read close to 5V. Decision: If not, check wiring back to the module; if wiring is good, consider module repair or replacement.

Common causes

  • Faulty engine shutdown switch
  • Wiring issues or short circuits
  • Poor connections at the module or sensor
  • Corrosion in connectors
  • Control module failure

Typical repair cost

$$$

Related codes

Frequently asked questions

Can I still drive the vehicle?

Not recommended. If this switch malfunctions, the engine could shut off unexpectedly.

Will this code come back after I clear it?

Yes, if the underlying problem isn't fixed, the code will likely return.

Why does this often pair with SPN 1490?

SPN 1490 indicates a related issue with the engine shutdown switch circuit, making them common to see together.

Working a real vehicle right now?

Let DiagCoach walk you through it live with your specific symptoms, vehicle, and what you've already checked.

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