What are the common causes of P04A3?

An intermittent break in the valve B wiring. A loose valve B connector. A valve B that sticks only at times. Water in the valve B connector.

Wiggle test the valve B wiring while watching the signal. Command the valve B through its range and watch for a dropout. Inspect the valve B connector for looseness or water. Replace the valve B if it sticks intermittently. Clear the code and retest.

P04A3

Exhaust Pressure Control Valve B Intermittent

System: Auxiliary emission controls (P code)
Lamp: Check Engine Light
Category: Powertrain - Auxiliary Emissions Controls

What it means

P04A3 means Exhaust Pressure Control Valve B Intermittent.

Where it lives

For P04A3, the description names the valve as the part involved.

Check these first

An intermittent break in the valve B wiring
A loose valve B connector
A valve B that sticks only at times
Water in the valve B connector

What to do next

Wiggle test the valve B wiring while watching the signal
Command the valve B through its range and watch for a dropout
Inspect the valve B connector for looseness or water
Replace the valve B if it sticks intermittently
Clear the code and retest

Look up another code

Code or symptom

Enter a full code or a symptom. Press / to search. How to read a code

Type a code above, or start from a symptom or a common code.

Updated

Generic SAE J2012 definition. Last updated 2026-10-10.