Getting a check engine light is frustrating, but getting one that prevents your car from starting is worse. A clear code P1374 explanation matters because this specific fault points directly to the engine's timing sensors. If you drive a General Motors vehicle like a Buick, Chevrolet, or Pontiac, this code usually means the 24X crankshaft position sensor is struggling to communicate with the powertrain control module. Ignoring it often leads to sudden stalling at low speeds, leaving you stranded.

What exactly does the P1374 diagnostic trouble code mean?

Your engine relies on multiple sensors to track timing accurately. The 3X and 24X crankshaft position sensors both send frequency signals to the computer. The 24X sensor is primarily active at lower engine speeds to smooth out the idle and improve starting reliability. When the powertrain control module sees a mismatch between the high and low frequency signals from these sensors, it triggers the P1374 code. Reading complex wiring diagrams for this system is much easier when you use a clean font like Montserrat on your digital service manual.

What symptoms will your car show?

You will usually notice driveability problems before or right after the check engine light turns on. The most common signs include:

  • Extended cranking times when starting a cold engine
  • Rough idle that feels like the car wants to stall
  • Sudden engine shut-off when driving under 1200 RPM
  • Reduced fuel economy

When you start experiencing these driveability issues, looking into the underlying mechanical or electrical faults is the best way to narrow down the problem before you replace parts.

Why do people misdiagnose this crankshaft issue?

A very common mistake is replacing the wrong sensor. GM engines often have both a 7X and a 24X crankshaft position sensor. Mechanics sometimes swap the 7X sensor because it is easier to access near the harmonic balancer, but P1374 specifically flags a problem with the 24X circuit located behind the crankshaft pulley. A solid understanding of the sensor correlation prevents you from throwing money at the wrong replacement part. Another mistake is assuming the sensor is dead when the actual problem is a chafed wire rubbing against the engine block.

How do you properly test and fix the circuit?

Testing this system requires an oscilloscope or a high-quality digital multimeter. You need to check the resistance of the 24X crankshaft position sensor. A typical good reading falls between 500 and 1500 ohms, but you should verify the exact specification for your specific vehicle model. Before you buy any replacement part, retrieving the full history of the engine fault will tell you if the issue is an intermittent wiring failure or a permanent sensor breakdown.

You should also inspect the reluctor wheel. If the wheel is damaged, bent, or has excessive metallic debris stuck to it, it will distort the magnetic signal regardless of sensor health. Clean the mounting area thoroughly before installing a new component.

Practical next steps for clearing the code

Follow this sequence to get your vehicle running smoothly again:

  1. Scan the system and write down all stored codes and freeze frame data.
  2. Visually inspect the wiring harness leading to the 24X sensor for heat damage, melting, or exposed copper.
  3. Measure the sensor resistance with a multimeter and compare it to the factory specifications for your exact make and model.
  4. Replace the 24X crankshaft position sensor and ensure it is seated fully against the block if the resistance is out of range.
  5. Clear the codes with your OBD2 scanner and test drive the vehicle at low speeds to verify the repair.