Firstly... big ups for the latest vid and "the truth about cars" sentiment! Legend 🙌
Good grief! The 2002 mazda bongo im working on has the dreaded P0401 code... I've had the whole intake off and its clear as a bell... swapped out the EGR valve itself, along with stepper motor... the EGR solenoid, cat seems fine (although unsure of replacement)... van runs fine even with check engine light on, when reset it takes around 4 days of driving around before coming back on (which makes diagnosis a looooong process)...
Im resorting to thinking about O2 sensor, idle control valve, charcoal canister etc but most of that stuff would effect its running.... and if it was ecu surely that would effect running also...
Bloody van doing my head in🤯
All searching pulls up stuff I've already ruled out ... any suggestions from scotty or the mods based on it running fine and taking days to throw a fault code, would be most appreciated!
Cheers
KD
How soon does the code come AFTER all "emisions rdy for testing completes (the drive cycle)" after reset? You should be able to complete a drive cycle in a day. Just trying to determine if the other emissions systems being "rdy" is a precondition to egr code being thrown and possibly some relation to a value the ecu is getting from another system. And do you know if it ever throws the code during closed loop operation?
@hillbilly
Thats what I thought, but for a good 3-4 days it said since clearing code it still said egr system tests incomplete, I checked it after light finally came on and it said all egr system passed! Im well bamboozled lol
@hillbilly
No idea re closed loop operation...
You should be able to see this on your scanner. Here's all it is, when you first start your car it's in "open loop" meaning that the engine is using stored values to set fuel mixture etc. Only after warm up will the pcm go to "closed loop" which is where the fuel mixture is continually being adjusted by feedback from O2 sensors, maf values, etc. So closed loop is simply the data feedback in a closed loop (open loop no feedback, just stored data). Google drive cycle for your Mazda and the steps on how the drive cycle is done exactly for that car should tell you how/what to do/drive to complete each of the cycles quickly(ish). Varies by car...