AutoFixDB - Free OBD-II diagnostic trouble code lookup. Find causes, symptoms, diagnostic steps and repair solutions.

Overview

OBD‑II trouble code P03B6 indicates that the cylinder 4 pressure sensor circuit is reporting a voltage higher than specified, suggesting a fault in the sensor, wiring, or control module on cylinder 4

Common Symptoms

Check Engine Light illuminated
Rough idle and vibrations
Reduced power and sluggish acceleration
Engine misfires or irregular combustion in cylinder 4

Most Common Causes

Faulty cylinder 4 pressure sensor medium

Sensor may send voltage above expected range triggering the code

Wiring or connector issues in the pressure sensor circuit medium

Short to power, open ground, or damaged insulation can cause erroneous high voltage

Engine control module (ECM) malfunction low

ECM may misinterpret sensor signal or have internal fault

Internal mechanical issue in cylinder 4 low

Unusual cylinder pressure caused by valve or compression issue may mimic sensor fault

Diagnostic Steps

Retrieve and record DTC with an OBD‑II scanner and capture freeze frame data

Expected: Code P03B6 recorded with relevant engine conditions

Interpretation: Confirmed presence of high circuit voltage condition
Inspect cylinder 4 pressure sensor wiring and connectors for damage, corrosion, or poor contacts

Expected: Wiring intact with secure, clean connections

Interpretation: Wiring fault likely if damaged or loose
Measure sensor signal voltage at PCM input (e.g., >4.84 V indicates high input)

Expected: Voltage within specification

Interpretation: High reading confirms sensor circuit high fault; proceed to test sensor
Test or replace cylinder 4 pressure sensor

Expected: Sensor responds within manufacturer specs

Interpretation: Replace sensor if out of range
If sensor and wiring are good, test ECM inputs and outputs for proper function

Expected: ECM processes correct signals

Interpretation: Replace ECM if confirmed internal fault

Repair Solutions

Replace faulty cylinder 4 pressure sensor medium

Estimated Cost: $150 - $400

Cost varies with vehicle model and sensor accessibility

Repair or replace damaged wiring/connector medium

Estimated Cost: $50 - $300

Includes labor to trace and correct shorts or opens

Replace and program ECM (if confirmed defective) hard

Estimated Cost: $800 - $1800

High cost due to module and programming labor

Common Misdiagnoses

Avoid these common diagnostic mistakes:

Confusing P03B6 with misfire codes (e.g., P0304) without verifying sensor circuit voltage

Frequently Asked Questions

Technical definition of P03B6 OBD-II Code

The P03B6 code stands for Cylinder 4 Pressure Sensor Circuit High. This generally indicates an issue with the Ignition system.

How serious is the P03B6 code?

With a severity level of medium, may cause rough idle, reduced performance, engine misfires, and illumination of check engine light

What are the symptoms of P03B6?

The most typical signs are: Check Engine Light illuminated, Rough idle and vibrations, Reduced power and sluggish acceleration.

What parts fail when P03B6 is set?

This code is frequently triggered by: Faulty cylinder 4 pressure sensor, Wiring or connector issues in the pressure sensor circuit, Engine control module (ECM) malfunction.

Is P03B6 expensive to fix?

The cost varies significantly based on the root cause. For example, replacing a Repair or replace damaged wiring/connector typically costs between $50 and $300, while fixing a Replace and program ECM (if confirmed defective) can range from $800 to $1800.

Is the P03B6 code specific to Dodge?

The P03B6 code is a generic powertrain code, meaning it applies to almost all makes and models, such as Honda, Toyota, VW, Ford, and Chevy.

P03B6: Cylinder 4 Pressure Sensor Circuit High