Seeing a P1374 trouble code on your scanner usually means your engine is struggling to track its own timing. This code points directly to a crankshaft position sensor correlation issue, meaning the engine control module is receiving erratic or missing signals from the sensors that tell it exactly when to fire the spark plugs. Understanding the exact P1374 error code causes matters because ignoring it can lead to sudden stalling at stoplights, rough idling, or a complete failure to start your vehicle.

What exactly triggers a P1374 code?

The P1374 code is heavily associated with General Motors vehicles. It indicates that the camshaft position sensor and the crankshaft position sensor are not agreeing on the engine's rotational position. Several distinct problems can cause this electrical mismatch.

• Failed Crankshaft Position (CKP) Sensor: This is the most frequent cause. The magnetic sensor itself degrades over time due to extreme under-hood heat and vibration, sending weak signals to the computer.
• Damaged Wiring or Connectors: The wiring harness routing near the crankshaft gets exposed to engine heat, oil leaks, and road debris. Frayed wires or corroded connector pins interrupt the electrical signal.
• Faulty Ignition Control Module (ICM): On older GM engines, the ICM processes the reference signal from the crank sensor. If the module fails, it triggers the code even if the sensor is perfectly fine.
• Bad Camshaft Position Sensor: Since the computer compares readings from both sensors, a failing cam sensor can falsely point the blame at the crank circuit.

Before replacing parts blindly, it helps to review the specific mechanical and electrical reasons behind the sensor failure to avoid throwing money at the wrong component.

How do you know if the crankshaft sensor is the actual culprit?

You cannot diagnose this issue just by looking at the code on a screen. You need to observe how the vehicle behaves. Drivers usually notice the engine hesitating during acceleration or stalling when coming to a stop. Sometimes the dashboard warning light behaves erratically or flashes right before the car actually dies on the road.

To confirm the cause, a mechanic will use an oscilloscope or an advanced OBD2 scanner to watch the live sensor data while cranking the engine. If the signal drops out randomly, the sensor or its wiring is at fault.

If you prefer to print out your live data logs to mark up voltage changes with a pen, choosing a highly legible typeface like Open Sans makes reading the small diagnostic numbers much easier on paper.

What are common diagnostic mistakes to avoid?

Many DIY mechanics see an engine code and immediately replace the most obvious part. With the P1374 code, this often leads to unnecessary repairs and lingering issues.

1. Ignoring the wiring harness: Replacing the crank sensor without inspecting the connector for oil contamination or broken wires will not fix the problem if the harness is the true cause.
2. Blaming the PCM right away: The powertrain control module rarely fails. Always rule out the sensors, the ignition module, and the wiring first.
3. Skipping the cam sensor: Because this is a correlation code, a failing camshaft position sensor can trigger the exact same fault.

Following a structured step-by-step vehicle evaluation keeps you from replacing perfectly good parts and getting frustrated when the check engine light returns.

What should you do next?

Once you understand the root causes, you can take direct action to get your car running smoothly again. Here is a practical sequence to follow this weekend:

• Check your engine oil level and look for active leaks around the crankshaft sensor wiring, as hot oil can degrade the electrical connections.
• Visually inspect the wiring harness connected to both the crankshaft and camshaft position sensors for any signs of chafing, melting, or green corrosion.
• Use a digital multimeter to test the resistance of the crankshaft position sensor and compare the reading to your vehicle's factory service manual specifications.
• Clear the code with your scanner and take the car for a test drive to see if the P1374 code returns immediately or only when the engine reaches operating temperature.
• If the wiring tests perfectly and the code persists, replace the crankshaft position sensor or the ignition control module based on your multimeter findings.