Timing Reference High Resolution Signal B Intermittent/Erratic Pulses
Code P0378 indicates the PCM detected intermittent or erratic pulses from the engine position sensor B (timing reference signal). This sensor provides critical timing data for engine synchronization, and signal irregularities can cause misfires and performance issues.
What You Might Notice
- Check Engine Light illuminated
- Engine misfires or hesitation during acceleration
- Rough idle or stalling
- Reduced fuel economy
- Difficulty starting the engine
Most Common Causes
- 1
Faulty engine position sensor B
The sensor itself may be failing or producing weak/inconsistent signals due to internal degradation or wear.
- 2
Wiring or connector issues
Corroded, loose, or damaged wiring connections to the sensor can cause intermittent signal loss or noise.
- 3
Contaminated or dirty oil
Oil sludge or debris can coat the sensor or reluctor wheel, disrupting the magnetic signal needed for proper operation.
- 4
Reluctor wheel damage or misalignment
Physical damage, cracks, or improper spacing between the reluctor wheel and sensor can produce erratic pulses.
How to Diagnose It
- 1
Check Faulty engine position sensor B — The sensor itself may be failing or producing weak/inconsistent signals due to internal degradation or wear.
- 2
Check Wiring or connector issues — Corroded, loose, or damaged wiring connections to the sensor can cause intermittent signal loss or noise.
- 3
Check Contaminated or dirty oil — Oil sludge or debris can coat the sensor or reluctor wheel, disrupting the magnetic signal needed for proper operation.
- 4
Check Reluctor wheel damage or misalignment — Physical damage, cracks, or improper spacing between the reluctor wheel and sensor can produce erratic pulses.
How to Fix It
- 1
Inspect and clean sensor connections
Check the engine position sensor B connector for corrosion, looseness, or damage. Clean contacts with electrical contact cleaner and ensure connections are tight.
- 2
Replace engine position sensor B
If the sensor is faulty or damaged, remove the old sensor and install a new OEM or quality aftermarket replacement in the correct location.
- 3
Inspect and service engine oil
Check oil level and condition; if contaminated or overdue for change, perform an oil and filter change to remove sludge and debris that may affect sensor operation.
- 4
Inspect reluctor wheel and sensor gap
Visually inspect the reluctor wheel for cracks or damage and measure the air gap between the wheel and sensor using a feeler gauge; adjust or replace components as needed.
Need a deeper diagnosis?
Search for related repair guides or browse by system.