help p0401

[zadam123]

How many such trips in total have you taken since replacing the EGR?

I have taken maby 3 like trips and then cleand out the egr passage with carb cleaner then drove 20 miles befor the light came on again.

how long or how many trips should i drive the car befor this light shuts off?

also the MAP sensor , where is it? is it easy to change?

[Paul_A]

All I can say is I had 401 persistently.... no matter what I did. New egr, cleaned the pipes, new gasket... everything I could think of..... turned out to be... yep ... intake manifold gaskets. Why the 401 though?? doesn't make sense

[89Vette]

I bet the MAP is in the intake...and the bad intake gaskets affected pressure readings during the EGR cycle.

Another thing to consider is a wiring problem for the EGR/MAP sensor. Any intermittent connection to those sensors would cause an issue.

[zadam123]

All I can say is I had 401 persistently.... no matter what I did. New egr, cleaned the pipes, new gasket... everything I could think of..... turned out to be... yep ... intake manifold gaskets. Why the 401 though?? doesn't make sense

how did you find out it was that?

[Y33TREKker]

I have taken maby 3 like trips and then cleand out the egr passage with carb cleaner then drove 20 miles befor the light came on again.

how long or how many trips should i drive the car befor this light shuts off?

Short of having actual Isuzu testing equipment, all I can say is that referring back to those same four sentences I mentioned last time is all that can be done.

"The number of test samples required...may vary according to..."

"Normally, the PCM will only allow for one EGR flow test sample to be taken during an ignition cycle." (Does this "ignition cycle" mean the entire time between when the engine is started and when it's finally shut off for that first test run after getting the new part put in? Depends on a persons' interpretation of "ignition cycle".

"To aid in verifying a repair, the PCM allows twelve test samples during the first ignition cycle following a Tech 2 "Clear info" or a battery disconnect."
How often does it take to run these twelve test samples? 20 minutes perhaps? I don't know.

"Between nine and twelve samples should be sufficient for the PCM to determine adequate EGR flow and pass the EGR test."
Could it possibly have taken around 20 minutes to take the nine-twelve samples that resulted in your EGR code being generated again even after you replaced the EGR valve? I don't know. Maybe someone will chime in with more info on how often these test samples are taken as an ignition cycle is occurring.