P0374
Timing Reference High Resolution Signal A No Pulses
If your code reader dashboard displays the generic DTC error code P0374, your vehicle is currently experiencing an active failure related to "Timing Reference High Resolution Signal A No Pulses". Proper system troubleshooting is required to safely clear this warning.
Driver's Summary
Code P0374 means your vehicle detected a problem with the timing reference high resolution signal a no pulses system. Typical symptoms include engine cranks but will not start, no tach signal. This is a serious fault — avoid extended driving and have your vehicle inspected by a mechanic as soon as possible to prevent further damage.
Symptoms
Engine cranks but will not start, no tach signal
Common Causes
- Dead high resolution sensor
- Unplugged connector
- Severed wiring harness
- Failed PCM
How to Fix
- 1 Replace high resolution sensor
- 2 Plug in connector securely
- 3 Repair cut wires
- 4 Test and replace PCM
Technical Explanation
Code P0374 is confirmed when the ECM's diagnostic algorithm detects a parameter deviation that persists across a defined number of consecutive drive cycles. For injector-specific codes, the ECM monitors the injector control circuit voltage drop during each pulse; a shorted or open injector presents a characteristic resistance signature that differs measurably from a healthy unit. The MIL illuminates after the fault is confirmed on two consecutive drive cycles, and the freeze frame data captured at first detection is stored in the PCM's memory for diagnostic reference.
Is It Safe to Drive?
An active P0374 code under high-severity conditions means the affected system is operating outside safe parameters. Continued driving — especially under load or at highway speeds — significantly increases the risk of secondary damage to components like unplugged connector.
Mechanic's Pro Tip
The most common mistake with P0374 is replacing the sensor without verifying the reference voltage and ground integrity first. Use a scan tool to monitor the sensor's live output; a truly failed sensor shows a stuck, flatlined reading — a sensor that fluctuates but reads slightly off usually indicates a wiring or vacuum issue, not a dead sensor. Always spray electrical contact cleaner on the connector pins before condemning the sensor.
Sensor replacement: 150 - 400