P0373 — Timing Reference High Resolution Signal “A” Intermittent/Erratic #

The code description may vary by manufacturer. Below are known variations from different OEMs:

• Timing Reference High Resolution Signal “A” Intermittent/Erratic (General, GM, Chrysler, Ford)
• Crankshaft Position Sensor “A” High Resolution Signal Intermittent (Toyota, Lexus)
• Engine Speed Sensor Signal “A” Fluctuates Intermittently (BMW, MINI)

Summary of code P0373 #

P0373 refers to an intermittent or erratic signal detected by the engine control module (ECM) from the high resolution timing reference sensor “A”. This sensor, often a crankshaft position sensor (CKP) or a camshaft position sensor (CMP), provides critical data for ignition timing and fuel injection. When the ECM senses irregularities or momentary dropouts in the signal, it will set this code. The result can be anything from minor drivability changes to significant performance loss, depending on the frequency and duration of the signal fault. Left unresolved, this issue may lead to more severe engine performance problems.

Common symptoms for code P0373 #

When the P0373 code appears, your vehicle may exhibit a range of issues, often related to engine performance and drivability. These symptoms can be intermittent, matching the nature of the fault itself, and might not always be present. Pay close attention to the following signs:

• Check Engine Light (CEL) illuminated
• Engine hesitation or stumbling during acceleration
• Intermittent misfires or rough idle
• Hard starting or occasional stalling
• Reduced engine power or poor throttle response
• Possible increase in fuel consumption

Likely causes for code P0373 #

The most frequent causes of P0373 relate to issues affecting the integrity of the high resolution timing signal. These may stem from the sensor itself, its wiring, or engine components that impact signal quality. Here are the most common causes, in order of likelihood:

1. Faulty or failing crankshaft or camshaft position sensor — the most common culprit, often due to age, heat, or oil contamination.
2. Damaged, corroded, or loose wiring/connectors at sensor “A”
3. Debris or metal shavings on the sensor or reluctor ring (the toothed wheel providing timing reference)
4. Reluctor ring (trigger wheel) with missing, damaged, or dirty teeth
5. ECM (Engine Control Module) internal fault (rare)
6. Aftermarket modifications causing electrical interference

Step-by-step diagnostic for code P0373 #

Diagnosing P0373 requires a methodical approach to isolate the root cause. Begin with the basics and work towards the more complex possibilities:

• 1. Retrieve all stored codes and freeze frame data using an OBD-II scanner to understand when the fault occurred.
• 2. Inspect the sensor “A” and its wiring harness for signs of damage, corrosion, oil contamination, or loose connections.
• 3. Clean the sensor and reluctor ring to remove any debris or metal shavings; re-inspect for physical damage.
• 4. Test the sensor output using a digital multimeter or oscilloscope to check for intermittent drops or erratic signal patterns.
• 5. Wiggle test the wiring while monitoring live data to see if movement triggers the fault.
• 6. Check the reluctor ring (if accessible) for missing or damaged teeth and proper alignment.
• 7. If all else checks out, consider ECM testing or reprogramming (usually as a last resort).

Possible repairs for code P0373 #

Based on the diagnosis, the following repairs are commonly performed to resolve P0373:

• Replace the crankshaft or camshaft position sensor if found faulty or contaminated.
• Repair or replace damaged wiring or connectors associated with sensor “A”.
• Clean or replace the reluctor ring (trigger wheel) if debris or damage is found.
• Reseat or tighten connectors to ensure good contact.
• In rare cases, replace or reprogram the ECM if proven faulty after all other checks.

Is it safe to drive with code P0373? #

Driving with code P0373 is not recommended for extended periods. While the vehicle may still run, there is a risk of sudden stalling, rough running, or even a no-start condition if the signal error worsens. Inconsistent timing data can lead to poor engine performance and increased emissions. If you must drive, do so cautiously and avoid demanding situations until the cause is properly repaired.

Vehicles most commonly affected by code P0373 #

P0373 is seen across a wide range of makes and models that use high-resolution timing sensors. The following vehicles are more frequently associated with this code, but it can occur on many others:

• Chevrolet Silverado, Suburban, Tahoe (GM V8 engines)
• Dodge Ram, Dakota, Durango (Chrysler V8 engines)
• Ford F-150, Mustang, Explorer (modular V8 and V6 engines)
• Toyota Tacoma, Tundra, 4Runner (V6 and V8 engines)
• BMW 3 Series, 5 Series (N52/N54 engines)

Many other models with advanced engine management systems may also report P0373 if timing reference issues are detected.

Common mistakes and best practices for code P0373 #

It’s easy to overlook the basics or jump to conclusions with P0373. Avoiding these pitfalls ensures a quicker and more accurate repair:

• Ignoring connector condition — a loose or corroded connector is a frequent but simple fix.
• Replacing the sensor without inspecting the reluctor ring for debris or damage.
• Skipping live signal testing — intermittent faults may not be visible with static checks alone.
• Assuming the ECM is at fault before thoroughly checking wiring and sensor operation.
• Not clearing codes after repair to confirm resolution.

Quick FAQ for code P0373 #

Still have questions? Here are answers to some of the most common concerns:

• Q: Will P0373 cause my car to not start?
  A: It can, especially if the signal loss becomes severe or constant. Early on, you may only notice minor drivability issues.
• Q: Can I just clear the code and keep driving?
  A: Clearing the code without fixing the underlying issue will only result in the code and symptoms returning. Proper diagnosis and repair are essential for safe operation.