P2618: Crankshaft Position Signal Output Circuit Low

What it means

The crankshaft position signal output circuit voltage is below the expected level.

At a glance

• Usually lights the check-engine light

How it works

The crankshaft position signal output circuit sends engine-speed and position timing information from the engine controller to a connected module or system. P2618 sets when voltage on that output circuit is below the expected level, commonly because the wire is shorted to ground or the output buffer has failed; it does not identify the receiving module.

Common causes

Most likely first.

1. Output wire shorted to ground
2. Buffer transistor failed
3. Connector pins corroded - high contact resistance

Symptoms

• Check-engine light
• Engine may crank longer, run poorly, or fail to start

How to diagnose it

1. Record freeze-frame data and related crankshaft or communication codes, and note whether starting or running changed when the fault appeared.
2. Inspect the crankshaft signal output harness and connectors for chafing, corrosion, loose pins, or damage that could ground the circuit.
3. With the circuit isolated as specified in service information, test the output wire for a short to ground.
4. Check continuity and connector terminal contact along the path between the controller and the receiving module.
5. If the wiring is sound, test the controller's output buffer using the manufacturer's procedure.

Common fixes

• Repair chafed crankshaft output-wire insulation that is shorting to ground.
• Clean and secure corroded or loose connector terminals.
• Repair damaged wiring or a poor connection along the signal path.
• Repair or replace the controller only if testing confirms a failed output buffer.

Can I keep driving?

If the engine runs normally, limited driving may be possible, but poor running, stalling, or a no-start can result if the crankshaft signal is disrupted. Stop driving if the engine stalls or becomes unreliable.