p400 ob2 code

[dav6.5td]

hello has all, I have an error code the p 400 which appears rather often now and I would like</span> to know if somebody already had this code and thus could give</span> me some councils</span> already to know or look at</span> and how to cure it.</span>
thank you in advance for your answers

[DmaxMaverick]

P400 isn't a valid code. If you have a P0400, it's a general EGR flow discrepancy. It could be vacuum related, EGR valve (stuck open/closed), or MAF fault. If you have no other codes present, try cleaning the MAF first, then check the EGR valve for sooting. Also verify you have system vacuum (~20") at the EGR valve line at idle, ECT up to operating temp (EGR active).

[dav6.5td]

hello,
I forgot to mention it but valve egr is condemned</span> and I installed</span> a pcm from heat diesel which normally removed</span> the function</span>.</span>
thus is this normal which the e value='altmeaning-,-34120,-,100'>[flaw] (Dictionnaire alternatif SYSTRAN)</choice><choice value='altmeaning-,-34121,-,100'>[frailty] (Dictionnaire alternatif SYSTRAN)</choice><choice value='altmeaning-,-34122,-,100'>[imperfection] (Dictionnaire alternatif SYSTRAN)</choice><choice value='altmeaning-,-34123,-,100'>[lack] (Dictionnaire alternatif SYSTRAN)</choice><choice value='altmeaning-,-34124,-,100'>[shortcoming] (Dictionnaire alternatif SYSTRAN)</choice><choice value='altmeaning-,-34125,-,100'>[snag] (Dictionnaire alternatif SYSTRAN)</choice><choice value='altmeaning-,-34126,-,100'>[vice] (Dictionnaire alternatif SYSTRAN)</choice><choice value='altmeaning-,-34127,-,100'>[weakness] (Dictionnaire alternatif SYSTRAN)</choice><source>défaut</source>" id="altmeaning_10">defect always appear</span>.</span>
how made you to check ~20” At the EGR valve line At idle, I does not see too much how to make</span>.</span>
and that is what you want to say by ~20”.
afflicted for all these questions.</span>

[dav6.5td]

hello,
I forgot to mention it but valve egr is condemned and I installed</span> a pcm from heat diesel which normally removed</span> the function</span>.</span>
thus is this normal which the defect always appear</span>.</span>
how made you to check ~20” At the EGR valve line At idle, I does not see too much how to make</span>.</span>
and that is what you want to say by ~20”.
afflicted for all these questions.</span></span>

[DmaxMaverick]

If you have EGR codes with a PCM that's supposed to have the function disabled, the PCM isn't correctly programmed. The EGR system should never be monitored.

If you have the EGR, or parts of the system, mechanically disabled or removed, there's no point trying to fix the code. You will have to either repair the EGR system, or have the PCM properly programmed or replaced. Or, always live with the SES lamp and the code.

On a functional EGR system, check the vacuum at the EGR valve actuator by removing the line and installing a vacuum gage. With EGR active, it should indicate the same vacuum as the pump output, which is ideally 20 inches HG or more. However, if your EGR system is disabled, and you have a mechanical controlled (non vacuum) wastegate, you don't need vacuum (or the pump and plumbing) on the truck, at all. The emission control system and the turbo wastegate control are the only uses for vacuum on 1994 and later trucks.