P0401 = INSUFFICIENT EGR FLOW


P0404 = EGR FLOW CIRCUIT RANGE/PERF FLOW SENSOR CIRCUIT LOW INPUT


P1404 = MANUFACTURER CONTROL AUXILLERY EMISSIONS CONTROL





I HAD A TOTAL OF 8 CODES. ALL OF THESE WERE SET TWICE. PICKED UP AN ACTRON OBD II AUTO SCANNER TODAY FROM ADVANCE AUTO FOR 150.00.

i have the same codes.no cat mrbp exhaust. same scanner it will clear all codes except auxillary emissions code. that you have to plug the egr back in for. mine were also done twice .set the engine light off.Edited by: gonemax

Any you were both gettin the check engine light?


DTC P0401 EGR Flow Insufficient


P0404 EGR Open Position Performance

Mine was on. Cleared it, came back on almost instantly.

Does anyone know the pinout on the wiring harness? Perhaps we could fool the EGR into thinking it is connected? If that idea was already posted, I apologize...haven't had time to scope all the threads on this EGR mod.

I can give you the pinout, but the computer sends a signal to the EGR motor, then compares the sensor expected value to the received value. If it is not correct, then the code will be set. I need to read more on it, but I think that there may be a way to do it and not get codes (although I'm not sure yet, give me a day or two), and that is to wait until after the truck is started, then disconnect the egr. A couple of concerns:


1. If you wait until after the truck is running, the EGR is not fully closed, and you disconnect it, will it return to fully closed. Max Power, I think I gathered from what testing you did, that it would in fact go closed.


2. I am not sure how often or when the EGR flow is tested, but I get the impression that it only checks it once on startup.


If this is the case, then you could very easily disconnect the amphenol or if you really wanted to get fancy schmancy, you could run a switch back to the cab and disconnect the valve open signal.


Any thoughts?
Dennis

I can give you the pinout, but the computer sends a signal to the EGR motor, then compares the sensor expected value to the received value. If it is not correct, then the code will be set. I need to read more on it, but I think that there may be a way to do it and not get codes (although I'm not sure yet, give me a day or two), and that is to wait until after the truck is started, then disconnect the egr. A couple of concerns:


1. If you wait until after the truck is running, the EGR is not fully closed, and you disconnect it, will it return to fully closed. Max Power, I think I gathered from what testing you did, that it would in fact go closed.


2. I am not sure how often or when the EGR flow is tested, but I get the impression that it only checks it once on startup.


If this is the case, then you could very easily disconnect the amphenol or if you really wanted to get fancy schmancy, you could run a switch back to the cab and disconnect the valve open signal.


Any thoughts?
Dennis

I think you might be on the trail. From a post from socaldieseltech:
EGR Valve Control Enabling Conditions.

Exhaust gas recirculation (EGR) valve control will only be enabled during idle and cruising conditions while the following conditions are met:

* The intake air temperature (IAT) is more than 5.25°C (41.5°F). EGR valve control will remain enabled until the IAT is less than 0°C (32°F) and will not enable again until the IAT is more than 5.25°C (41.5°F).
* The engine coolant temperature (ECT) is between 60-96.75°C (140-206.15°F). EGR valve control will remain enabled until the ECT is less than 57°C (134.6°F) or more than 99.75°C (211.55°F) and will not enable again until the ECT is between 60-96.75°C (140-206.15°F).
* The barometric pressure (BARO) is more than 74 kPa. EGR valve control will remain enabled until the BARO is less than 72 kPa and will not enable again until 74 kPa.

So it look like you need to be warmed up, not to cold outside and need to check the barometer. This diagnostic only runs once per cycle. Probably could cobble up a self latching relay powered off the switched ignition so it drops every cycle. Latch the relay with a momentary push button and you should be a-okay.

The troubling one might be the P1404. socaldieseltech posted info on that on the first page of Max Powers thread. It indicated the diagnostic for that ran continously.

Good thoughts. Hope my manual shows up soon.

Jim