2006 Grand Caravan 3.8L Engine Running Poorly After New EGR Installation – Code P0404 and Power Loss

If you disconnect the EGR valve's electrical connector, does the engine run better? A properly functioning EGR valve should remain closed when no power is supplied to it. It only opens briefly at specific RPMs during certain driving conditions to allow exhaust gases into the intake manifold. This behavior helps regulate emissions and engine temperature.

Code P0404 is not a simple flow issue—it indicates an EGR system malfunction, but it doesn't confirm whether the valve or circuit is faulty. Even with a new EGR valve, defects can occur in components like the solenoid or position sensor circuits. The EGR valve assembly has five wires: three for the position sensor (5V reference, ground, and signal), and two for the solenoid. A 5V supply and solid ground are required for proper sensor operation; the signal wire must be intact with no open or short circuits. The solenoid receives power from the PCM—only when commanded—and uses pulse-width modulation to control valve opening. If any wiring is damaged or there's a short/open, it can trigger P0404. If all electrical checks pass, a faulty PCM may be the root cause. A scan tool with bi-directional controls and an understanding of EGR circuit design would greatly assist in diagnosing this issue.

Thanks! I’ll try disconnecting the EGR electrical connector to see if the engine runs better—this is a helpful test to determine whether the valve or its control system is at fault.

AAP stands for Advance Auto Parts. They performed a diagnostic using their scan tool, which flagged the EGR control circuit as faulty. I’m now considering investing in a dedicated OBD2 scanner with bi-directional controls to get more accurate readings. This would allow me to monitor real-time EGR valve position and command signals from the PCM.

I have a 2006 Grand Caravan 3.8L with 74,000 miles. I recently installed a new EGR valve and cleaned the tube—no major blockage. It ran better for one day before the check engine light came on and performance dropped significantly. The AAP scan tool identified a 'EGR control circuit' fault (P0404).

Not all OBD2 scanners support bi-directional controls—these are essential for diagnosing EGR systems. Testing can be done manually with a digital multimeter and access to the correct wiring pins (available at hardware stores like Walmart’s Craft section). You’d need to check voltage levels, signal integrity, and even manually energize the solenoid while monitoring engine RPM and PCM signal changes simultaneously. While this requires some technical skill and tools, it's feasible if the PCM is accessible. A DC voltmeter, jumper wire, and basic knowledge of circuit operation would make this possible.

I tried disconnecting the EGR electrical connector—no improvement in engine performance whether plugged in or unplugged. I also ran a small amount of Sea Foam through the system, which reduced smoke slightly but didn’t resolve the power loss issue.