P0374 – Timing Reference High Resolution Signal “A” No Pulse

P0374 is a diagnostic trouble code that points to a problem with how your engine computer reads crankshaft position. In simple terms, the ECU is seeing an irregular or missing signal from the crankshaft position sensor, so it can’t reliably track engine speed and timing. That can cause hard starting, misfires, or even a no-start condition. While this code sounds intimidating, it’s usually caused by a bad sensor, wiring issue, or damaged reluctor ring. With a methodical approach, you can pinpoint the fault and avoid throwing parts at the problem.

What Does P0374 Mean?

P0374 stands for “High Resolution Timing Reference Signal ‘A’ – No Pulses” (wording may vary slightly by manufacturer). Your engine uses a crankshaft position (CKP) sensor and a toothed wheel or reluctor ring to generate a high-resolution signal. The ECU expects a specific pattern of pulses as the crankshaft spins.

When the ECU detects that the high-resolution timing signal is missing, erratic, or not matching expected engine speed, it sets code P0374. This is a serious timing reference fault because the ECU relies on that signal for fuel injection and ignition timing.

Quick Reference

• Code: P0374
• Meaning: High-resolution crankshaft timing signal “A” has no pulses or is not being detected
• Primary system: Crankshaft position / engine timing
• Typical causes: Faulty CKP sensor, wiring issues, damaged reluctor ring, ECU fault
• Severity: Moderate to severe – can lead to stalling or no-start

Real-World Example / Field Notes

In the shop, I usually see P0374 on vehicles that come in with intermittent stalling or crank-no-start complaints. One common scenario: the car starts fine cold, but after 15–20 minutes of driving it stalls at a light and won’t restart until it cools down. Scan data shows engine RPM dropping to zero even while cranking, and P0374 stored. In several of these cases, the crankshaft position sensor was heat-soaked and failing intermittently. Replacing the sensor and cleaning the connector fixed the issue, but on a few vehicles we also found cracked wiring insulation near the sensor from road debris and oil contamination.

Symptoms of P0374

• Hard starting – extended cranking time before the engine finally fires, especially when hot.
• No-start condition – engine cranks but will not start because the ECU can’t see a valid crank signal.
• Engine stalling – sudden stall while driving or when coming to a stop, sometimes restarting after a cool-down.
• Rough running – misfires, hesitation, or poor acceleration due to incorrect ignition and fuel timing.
• Erratic tachometer – RPM gauge drops out, jumps, or reads zero while the engine is still turning.
• Reduced power – limp mode or limited RPM as the ECU uses backup strategies to protect the engine.
• Check Engine Light – MIL on solid, sometimes with additional misfire or cam/crank correlation codes.

Common Causes of P0374

Most Common Causes

• Failed crankshaft position sensor (CKP) – internal sensor failure, often heat-related, is the top cause. The sensor may work cold and fail when hot.
• Damaged or loose reluctor ring / tone wheel – missing teeth, cracks, or a slipped ring on the crankshaft can disrupt the pulse pattern.
• Wiring issues at the CKP sensor – broken wires, corrosion in the connector, or high resistance in the signal or ground circuits.
• Oil or metal debris on sensor tip – contamination can interfere with the magnetic field and weaken the signal.
• Poor sensor mounting or incorrect gap – if the sensor is not seated fully or the air gap to the tone wheel is out of spec, the ECU may lose pulses.

Less Common Causes

• ECU/PCM internal fault – rare, but a damaged input circuit can misread a good sensor signal.
• Aftermarket performance parts – lightweight flywheels, incorrect tone wheels, or modified crank pulleys can cause an incompatible signal.
• Previous engine work errors – incorrectly installed crankshaft, reluctor ring pressed on backwards, or misaligned timing components.
• Grounding issues – poor engine or chassis grounds causing unstable reference voltage or signal noise.
• Moisture intrusion – water in connectors or harness sections near the front of the engine or under the vehicle.

Diagnosis: Step-by-Step Guide

To diagnose P0374 properly, you’ll want a quality scan tool, a digital multimeter, and ideally an oscilloscope. A service manual or wiring diagram for your specific vehicle is also very helpful. If you don’t have advanced tools, you can still do basic visual and resistance checks before heading to a shop.

1. Confirm the code and gather data. Connect a scan tool, verify P0374 is present, and check for related codes (like cam/crank correlation or misfire codes). Look at freeze-frame data to see engine RPM, temperature, and speed when the code set.
2. Check live RPM while cranking. With the scan tool on live data, crank the engine. If RPM shows 0 while the starter is turning, the ECU is not seeing a valid crank signal, which strongly points to the CKP sensor or its circuit.
3. Perform a visual inspection. Locate the crankshaft position sensor (often near the crank pulley, transmission bellhousing, or rear of engine). Inspect the connector, wiring, and sensor body for damage, oil saturation, or loose mounting.
4. Inspect the reluctor ring / tone wheel. If accessible, look for missing teeth, cracks, or heavy rust. On some engines, this requires removing covers or using a borescope through an inspection port.
5. Check sensor power, ground, and signal circuits. Using a wiring diagram, back-probe the connector with a multimeter. Verify the reference voltage and ground are within spec. Check continuity and resistance from the sensor connector back to the ECU.
6. Measure sensor resistance (if applicable). Many magnetic CKP sensors have a specified resistance range. With the sensor unplugged, measure across the terminals and compare to spec. An open or shorted sensor is faulty.
7. Scope the crank signal (advanced). If you have an oscilloscope, monitor the CKP signal while cranking and idling. You should see a clean, repetitive waveform. Missing segments, noise, or dropouts confirm a sensor or tone wheel problem.
8. Check Mode $06 data. Some vehicles store detailed misfire and crank/cam correlation test results in Mode $06. This can help confirm if the ECU is intermittently losing the crank signal under certain conditions (heat, vibration, RPM).
9. Heat test (intermittent issues). If the problem only occurs hot, you can gently heat the sensor area with a heat gun (carefully) while monitoring signal or RPM on the scan tool to reproduce the failure.
10. Rule out ECU issues last. Only after confirming good sensor, wiring, and tone wheel should you suspect the ECU. At that point, professional testing or ECU substitution may be required.

Pro tip: Always clear the code and perform a proper road test after each repair step. An intermittent P0374 can seem “fixed” in the bay but come right back under load or at highway speeds.

Possible Fixes & Repair Costs

Most P0374 repairs center around restoring a clean, reliable crankshaft position signal. Typical fixes include:

• Replacing the crankshaft position sensor
• Repairing or replacing damaged wiring or connectors in the CKP circuit
• Cleaning sensor and mounting surface, correcting air gap
• Replacing a damaged or slipped reluctor ring / tone wheel
• Reprogramming or, rarely, replacing the ECU

In terms of cost, a basic CKP sensor replacement at a shop usually runs about $150–$400 parts and labor, depending on vehicle and sensor location. Wiring repairs can range from $100–$300. Replacing a reluctor ring or tone wheel may involve significant labor (transmission or timing cover removal), often $400–$900 or more. An ECU replacement and programming can exceed $600–$1,200. Labor rates, parts brand, and how buried the components are all affect the final bill.

Can I Still Drive With P0374?

You might be able to drive with P0374 for a short period, but it’s risky. If the crank signal cuts out completely while driving, the engine can stall unexpectedly, which is dangerous in traffic. Even if it doesn’t stall, you may experience rough running, poor performance, and increased fuel consumption. If the vehicle is starting and running, drive it only as needed to get to a repair facility, and avoid long trips or high-speed highway driving until the issue is resolved.

What Happens If You Ignore P0374?

Ignoring P0374 can lead to frequent stalling, hard starting, or a complete no-start situation that leaves you stranded. Over time, misfires and incorrect timing can stress ignition components and the catalytic converter. In the worst case, a failing crank signal at high RPM could cause severe drivability issues and unsafe loss of power.

Last updated: February 13, 2026

Vehicles Commonly Affected by P0374

P0374 can show up on many OBD-II vehicles, but it’s more common on certain platforms. You’ll often see it on GM products (Chevrolet, GMC, Cadillac, Buick) with V6 and V8 engines that use high-resolution crank sensors. It’s also seen on some Dodge/Chrysler/Jeep models, especially trucks and SUVs, as well as certain Ford pickups and SUVs. A few Nissan, Honda, and Toyota models can set this code too, usually when the crank sensor or tone wheel is worn or contaminated.