P03B4

Symptoms

• Check Engine light on
• Minor misfire or erratic operation
• Slight reduction in engine power
• Slight degradation in fuel economy
• Increased emissions during inspection

Causes

• Faulty cylinder 4 pressure sensor (misadjustment, performance drift)
• Damage to the wiring or sensor connector
• Sensor contamination (carbon deposits, oil)
• Problems with power or grounding of the sensor circuit
• Cylinder 4 mechanical problems affecting signal

How to Fix

1. Compare cylinder 4 sensor readings with other cylinders via data scanner
2. Check the wiring and connector of the sensor for damage
3. Check signal quality with an oscilloscope
4. Clean the sensor connector and check the contacts
5. Replace cylinder 4 pressure sensor
6. Check compression and other parameters of cylinder 4 to exclude mechanical causes

Related codes

Error P03B4 by Vehicle Brand