2010 Dodge Caravan P040-5 Code: Persistent EGR Circuit Low Issue After Valve and Sensor Repairs

I own a 2010 Dodge Caravan with 435,000 kilometers. It has generally run reliably until about three weeks ago when it stalled and required towing. Multiple diagnostic codes appeared, including issues related to the camshaft position sensor, APP sensor, and throttle body assembly. After replacing these components, all associated codes cleared. However, a new code—P0405 (EGR Circuit Low)—emerged and persists even after installing a new EGR valve. The vehicle occasionally enters a 'safe mode' where it will only operate at 20–30 km/h. This behavior resolves when the engine is turned off and restarted, with no further symptoms until the next occurrence. The P0405 code remains the only one present after each restart. At this point, both I and the repair shop have exhausted common troubleshooting steps. Possible solutions we're considering include replacing the EGR wiring harness or the Powertrain Control Module (PCM). However, no clear fix has been identified yet. Any insights or experiences with P0405 on a 2010 Dodge Caravan would be greatly appreciated.