Engine

P0374 — Timing Reference High Resolution Signal 'A' No Pulses

Severity: high Drive with care, to a shop

What P0374 means

The engine control module uses the crankshaft or camshaft position sensor ('A' reference) to know the position and speed of the engine's rotating shafts. That signal sets ignition and fuel injection timing. P0374 sets when the high-resolution pulses from that sensor are missing while the engine should be turning.

Symptoms

  • Check Engine light on
  • Hard starting or no start
  • Rough idle
  • Intermittent stalling
  • Reduced power
  • Misfires if the signal is unstable

Possible causes

  1. Failed crankshaft or camshaft position sensor (the 'A' reference)
  2. Open, shorted or corroded wiring or connectors
  3. Damaged, dirty or shifted reluctor/tone wheel
  4. Poor ground or electrical interference in the sensor circuit
  5. Missing sensor power or reference voltage
  6. Faulty ECM (uncommon)

How to diagnose

  1. Scan for codes and freeze frame data, and look for other crank or cam sensor codes
  2. Inspect the sensor, connector and harness for oil, chafing, corrosion and loose fit
  3. See whether the scan tool or tach shows RPM while cranking
  4. Check sensor power, ground and reference voltage at the connector with a multimeter
  5. Test the sensor resistance (inductive type) or scope its signal against specs
  6. Inspect the tone wheel for damaged or missing teeth, debris and metal shavings, and check the sensor air gap
  7. Check the signal wire continuity to the ECM and confirm cam/crank timing is correct
  8. If everything checks out, test the ECM and its power supply

Common fixes

  • Replace the crankshaft or camshaft position sensor
  • Repair or replace damaged wiring and connectors
  • Replace or properly reinstall the tone wheel
  • Restore the sensor ground and power supply
  • Reprogram or replace the ECM if confirmed faulty

Questions and answers

What does P0374 mean?

The ECM is not getting high-resolution pulses from the 'A' timing reference sensor, usually the crank or cam sensor. Without it, the ECM cannot time ignition and injection accurately.

Can I drive with P0374?

It is risky. The engine can stall while driving or refuse to restart. Have the sensor and wiring checked as soon as possible.

What most often causes P0374?

Most often it is the position sensor itself or its wiring and connector. A damaged tone wheel or the ECM is less common.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.