Finding a P1374 code on your OBD2 scanner usually points to a communication breakdown between your engine's crankshaft position sensor and the powertrain control module (PCM). Understanding vehicle code P1374 causes matters because ignoring this fault can lead to sudden stalling, poor fuel economy, or an engine that simply refuses to start. You need to pinpoint the exact broken component rather than guessing and throwing expensive replacement parts at the problem.

What exactly triggers the P1374 error code?

The P1374 fault generally means the PCM is seeing an incorrect frequency signal from the 24x crankshaft position sensor. Your car's computer relies on this 24x reference signal to calculate precise ignition timing and fuel delivery. Before grabbing your tools, checking how the manufacturer defines this specific code helps clarify your diagnostic steps. When the sensor fails to provide the correct high-to-low frequency correlation, the computer defaults to a backup system and triggers the check engine light.

Which broken parts usually cause a P1374 code?

The root cause is almost always electrical or sensor-related. You will typically find the problem in one of these specific areas:

  • A failing 24x crankshaft position sensor: This is the most common culprit. The internal components of the sensor degrade over time, causing it to drop the signal entirely or send erratic data to the computer.
  • Damaged wiring harnesses: The wires leading to the sensor run close to hot engine components. Heat, vibration, and age can cause the insulation to melt, leading to short circuits.
  • Corroded or loose connectors: Moisture and road salt easily penetrate the electrical plug at the sensor. Corrosion increases electrical resistance and distorts the voltage signal.
  • Faulty ignition coils: In some specific engine designs, a bad ignition coil can create electromagnetic interference that scrambles the crankshaft sensor signal. A failing sensor often creates noticeable drivability issues, which we cover when discussing what happens when this error triggers under load.
  • PCM failure: While rare, the computer itself can fail internally and fail to process a perfectly good signal from the sensor.

Why does my car throw a P1374 code only sometimes?

Intermittent codes are frustrating but usually point directly to wiring issues. When the engine heats up, metal expands. A wire with a tiny internal break might separate just enough to drop the signal when hot, then reconnect once the engine cools down. Oil leaks from the intake manifold gasket can also slowly seep into the sensor connector, creating an intermittent short. Getting a clear picture of how your car's computer interprets this fault prevents you from misdiagnosing a wiring glitch as a dead computer, so it helps to review the logic the PCM uses to set the code.

What mistakes do people make when fixing this?

Many DIY mechanics immediately replace the crankshaft position sensor without testing the wiring first. If a wire is chafed against the engine block, a brand new sensor will not fix the check engine light. Another common error is buying cheap, unbranded replacement sensors. The PCM requires highly precise voltage readings, and aftermarket sensors often fail right out of the box or degrade within a few months.

How should you actually diagnose the cause?

You need a digital multimeter to verify the electrical circuit. Start by locating the 24x crankshaft position sensor, usually found behind the harmonic balancer or near the crankshaft pulley. Disconnect the plug and check for a clean 12-volt supply, a solid ground, and an intact signal wire leading back to the PCM. Look closely at the sensor tip for metal shavings, which can accumulate and block the magnetic field.

Keeping track of your multimeter readings is just as important as taking them. If you build a physical binder for your repair notes and wiring diagrams, formatting your printed pages with a highly legible typeface like Roboto helps prevent misreading voltage specifications in a dimly lit garage.

What to do next

Follow this checklist to isolate the vehicle code P1374 causes safely and accurately:

  1. Scan the vehicle for additional codes to see if a secondary issue, like a camshaft sensor fault, is present.
  2. Visually inspect the sensor wiring harness for melted insulation, exposed copper, or oil contamination.
  3. Unplug the sensor and test the connector pins for proper reference voltage and ground.
  4. Check the sensor tip for debris and inspect the reluctor wheel on the crankshaft for physical damage.
  5. Replace the 24x crankshaft sensor with an OEM part if the wiring tests good but the sensor output is erratic.
  6. Clear the code with your OBD2 scanner and test drive the vehicle until it reaches operating temperature to ensure the fault does not return.