P0374 Code: Meaning, Symptoms, Causes & Fix

Overview

Code P0374 indicates a fault in Timing Reference High Resolution Signal A No Pulses, typically within engine synchronization and valve timing.

Symptoms

rough running or misfire
hard start when cold
loss of power at mid/high RPM

Common causes

Reference/ground fault affecting timing reference high resolution signal a no pulses
Signal biased high from short-to-voltage
Connector pin damage/corrosion or harness stress near related components

How to diagnose P0374

Confirm P0374 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to timing reference high resolution signal a no pulses for obvious defects.
Compare live data against expected upper threshold and verify reference voltage.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P0374

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with P0374?

Most vehicles can be driven short-term with P0374, but postpone heavy load/highway driving until repaired.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (high) in the timing reference high resolution signal a no pulses circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify P0374 remains cleared under the conditions that originally set the code.

Fix options

Perform relearn/adaptation if required.
Verify reference voltage and inspect wiring.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$300-$1400

Common mistakes when diagnosing P0374

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

P0374 in common vehicles

P0374 appears across makes such as Mazda, Subaru, Lexus, Jeep. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P0374?

P0374 is commonly set by high faults affecting timing reference high resolution signal a no pulses.

How much does it cost to fix P0374?

For P0374, repair costs are typically $300-$1400 depending on exact root cause, labor rates, and part quality.

Can I clear P0374 without repair?

You can clear P0374 temporarily, but the code usually returns until the underlying fault is corrected.