When your car stalls at a stoplight or cranks without starting, scanning the computer often reveals a specific fault. Understanding vehicle code P1374 causes is the difference between replacing a fifty-dollar sensor and wasting hundreds on unnecessary repairs. This code points directly to the engine timing system, meaning the computer is losing track of the crankshaft position. Without that tracking, the engine cannot time the spark plugs or fuel injectors properly, leading to immediate drivability issues.

What does the P1374 code mean for your engine?

In most General Motors vehicles, this trouble code indicates a problem with the 3x reference signal circuit. The crankshaft position sensor generates this signal to tell the ignition control module and powertrain control module exactly where the engine is in its rotation. When figuring out the underlying definition of this fault, you are usually looking at a breakdown in communication between the crank sensor and the engine computer. The high-frequency signal is either missing, erratic, or dropping out entirely.

What are the most common causes of code P1374?

The root of the problem usually falls into one of four categories. Identifying the exact culprit requires looking at the physical components and the electrical signals they produce.

  • Faulty crankshaft position sensor (CKP): Over time, the internal magnets or wiring inside the sensor degrade. Heat from the engine block accelerates this wear, causing the sensor to fail intermittently before dying completely.
  • Damaged wiring or connectors: The wiring harness runs close to moving engine parts and hot exhaust components. Chafed wires, melted insulation, or corrosion inside the sensor connector can interrupt the 3x reference signal.
  • Ignition control module (ICM) failure: The CKP sensor sends its signal directly to the ICM on many older engines. If the module itself is failing, it will not process the signal correctly, triggering the P1374 code.
  • Issues with the reluctor wheel: The sensor reads notches on a metal ring called the reluctor wheel. If debris gets stuck in the notches, or if the wheel becomes damaged or misaligned, the sensor cannot read the rotation accurately.

What symptoms tell you it is time to check the CKP sensor?

You typically will not see a P1374 code during routine maintenance. It shows up when the car starts acting up. You might experience hard starting, sudden stalling while driving, or a rough idle that feels like a misfire. In severe cases, the engine will crank but refuse to start at all because the computer does not know when to fire the spark plugs.

Keeping a printed copy of the factory wiring diagram in the garage makes troubleshooting much easier. If you type up your own notes or print diagnostic flows, setting your document to a highly legible typeface like Open Sans helps prevent eye strain when you are reading under a work light. Clear documentation helps you trace the exact wire colors and pinouts required for testing.

Common mistakes people make when fixing P1374

A frequent error is replacing the powertrain control module right away. The PCM is rarely the source of this fault. Another mistake is swapping the crank sensor without checking the wiring harness first. If a wire is broken near the connector, a new sensor will not fix the problem, and you might even damage the new part if there is a short circuit.

How to approach the repair

Before buying parts, you need to verify where the signal is dropping. If you are unsure how to use a multimeter or oscilloscope for this specific test, reviewing methods for testing the circuit will give you a reliable starting point. You will generally check for a solid ground and a 12-volt reference at the sensor connector, then test the signal wire for an alternating current voltage while the engine cranks.

Once you find the broken component, clearing the code and running the engine will confirm the fix. Sometimes you need to perform a crankshaft position variation learn procedure with a scan tool after installing a new sensor. Getting more context on how this specific system operates for your exact make and model will tell you if that relearn step is mandatory.

Next steps to clear the code

Follow this checklist to safely resolve the issue without guessing:

  1. Scan the vehicle to confirm P1374 is the active code and check for any accompanying misfire codes.
  2. Visually inspect the wiring harness leading to the crankshaft position sensor for burns, cuts, or oil contamination.
  3. Disconnect the sensor and check the connector pins for corrosion or looseness.
  4. Test the sensor resistance and signal output with a digital multimeter according to your service manual.
  5. Replace the faulty component, whether it is the sensor or a section of wiring.
  6. Clear the codes with your scanner, start the engine, and test drive the vehicle to ensure the check engine light stays off.