Just went to check codes on my 04.5 LLY truck and had those two codes, truck has Banks exhaust no cat, intake and Quad 120. Truck smoke HEAVILY on 90 and 120 setting. Any info would be great


Thanks

<H1>DTC P0401</H1><A name=ss1-1369740><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1369740&amp;psdid=437&amp;evc=sm#ss1-1369740" target="_blank">
<H5>Circuit Description</A></H5>


The engine control module (ECM) tests the exhaust gas recirculation (EGR) flow once per ignition cycle. When the proper enabling conditions are met, the ECM will close the EGR valve and then open the EGR valve while monitoring the mass air flow (MAF) signal. An expected MAF difference should be detected between the open and closed positions. If the ECM does not see the expected MAF difference, DTC P0401 sets.<A name=ss2-1369740><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1369740&amp;psdid=437&amp;evc=sm#ss2-1369740" target="_blank">
<H5>DTC Descriptor</A></H5>


This diagnostic procedure supports the following DTC.


DTC P0401 Exhaust Gas Recirculation (EGR) Flow Insufficient<A name=ss3-1369740><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1369740&amp;psdid=437&amp;evc=sm#ss3-1369740" target="_blank">
<H5>Conditions for Running the DTC</A></H5>
<UL =BULLET>
<LI>DTCs P0101, P0102, P0103, P0112, P0113, P0116, P0117, P0118, P0335, P0336, P0340, P0341, P0370, P0374, P0500, P0642, P0643, P2122, P2123, P2127, P2128, P2132, P2133, P2138, P2139, P2140, P2227, P2228, P2229 are not set.
<LI>The engine is running for more than 0.5 seconds.
<LI>The ignition voltage is between 11-18 volts.
<LI>The calculated fuel rate is between 3-20 mm³. This running condition will remain enabled until the calculated fuel rate is less than 2 mm³ or more than 25 mm³ and will not enable again until the calculate fuel rate is between 3-0 mm³.
<LI>The intake air temperature (IAT) is more than 5.25°C (41.5°F). This running condition 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).
<LI>The engine coolant temperature (ECT) is between 60-96.75°C (140-206.15°F). This running condition 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).
<LI>The barometric pressure (BARO) is more than 74 kPa. This running condition will remain enabled until the BARO is less than 72 kPa and will not enable again until 74 kPa.
<LI>The engine speed is between 640-820 RPM. This running condition will remain enabled until the engine speed is less than 580 RPM or more than 880 RPM and will not enable again until the engine speed is between 640-820 RPM.
<LI>The accelerator pedal position (APP) indicated angle is 0 percent.
<LI>The vehicle speed is less than 0.4 km/h (0.25 mph).
<LI>The power take-off (PTO) is not engaged.
<LI>The ECM is not in limp home mode.
<LI>The above conditions are present for 10 seconds.
<LI>This diagnostic runs once per ignition cycle while the above conditions are met. </LI>[/list]<A name=ss4-1369740><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1369740&amp;psdid=437&amp;evc=sm#ss4-1369740" target="_blank">
<H5>Conditions for Setting the DTC</A></H5>


The MAF difference monitored by the ECM during the EGR flow test indicates an insufficient amount of EGR flow.<A name=ss5-1369740><A href="http://service.gm.com/servlets/BlobShtml?ShtmlFile=1369740&amp;psdid=437&amp;evc=sm#ss5-1369740" target="_blank">
<H5>Action Taken When the DTC Sets-California</A></H5>
<UL =BULLET>
<LI>The control module illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.
<LI>The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating co

so when you take off the cat it sets off error codes? Does the check engine lt. come on? Is having the cat off bad for it? any backpressure issues?


THanks,


Jared

That's the same insufficient EGR code another member got when he removed his CAT. Different brand exhaust than yours. Another member has done as you did only with an ATS exhaust and has not had a problem.


Diesel Tech's right on this, as to why some trucks do it and others don't is still a mystery as far as I can tell. But as more folks try it I imagine we'll get a better idea of what might be causing it with one truck but not another.


IIRC, the F**d's have this problem too...Edited by: Zeeb

The Ford guys just disconnect their EGR's. Problem solved!

no cat is your problem....thats why juice is taken its time to release its program.with out that back pressure the turbo will run different as well as the egr....

If I read this correctly both of the codes set if the PTO isn't used, why not jumper the PTO wire so it doesn't check the egr flow.


It will think u have pto on all the time.


Eric or techs, do u think that will work?Edited by: Dmax Tim