2004-2005 LLY 6.6L Diesel EGR DTCs P0401 or P0404 - keywords idle rough smoke #PIP3256B - (Mar 22, 2005)

2004-2005 LLY 6.6L Diesel EGR DTCs P0401 or P0404



The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in the PI.

Condition/Concern:

Vehicle may be brought in for SES or MIL light on. Upon inspection of the vehicle, the technician may find EGR DTCs P0401 or P0404.

Recommendation/Instructions:
<LI type=1>Complete the proper SI diagnostics for the DTCs found. <LI type=1>If normal SI diagnostics have been completed and were inconclusive, inspect for any exhaust, air intake, or wiring harness modifications made to the vehicle. Modifications may induce EGR codes. <LI type=1>There has been a calibration released to address the concern of intermittent DTCs P0401 and P0404.
The new calibration will address DTCs P0401 and P0404 when the codes are set with no engine driveability concerns. If P0401 or P0404 are set and there is a customer concern of low power or black smoke, monitor the EGR valve and MAF sensor readings during the concern. A sticking EGR valve or skewed MAF sensor reading may also cause an intermittent P0401 or P0404 to set.
Please follow this diagnosis process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.
Moderators: You may want to put this in the TSB section, but I put it here only because it is specific to LLY...

i just got my truck back from the dealer on this exact issue. SES light came on. Had noticed that every once and a while when i put my foot into it there was not down shift, no pull like it used to have. not a single mod in this thing and it set off the 401 and 404. dealer replaced the EGR valve actuator assembly. read dealer invoice and got scared as hell until i saw this. " Also found an updated powertrain control module calibration for diagnostic enhancement for codes p0401 p0404. Reflashed PCM and road tested vechile. Ok." so was freakin out when i saw that as i have not done anything to my truck and thought that this quote regarded an installation of a chip. wheew. And the end result ....i will say this, holy crap the power is back big time!!!!:ro)

I guess the question of will the dealer refuse warranty work based on any of the mods listed above allow them to refuse to do any work on the rig? I recently had my muffler taken off but the cat is still in place. Within 20 miles it threw a light that will be addressed Monday when I take it in for a reflash that's available for my rig. I've never dealt with this dealer so I hope they're cool about the straight pipe...fingers crossed!