EGR operation

andrewlikeshisrokandrewlikeshisrok Junior Member
edited October 2018 in Engine
How does the EGR in the 2L amarok operate - vacuum to the EGR valve opens it allowing exhaust through the EGR?
I noticed that there is vacuum to the EGR valve at idle on cold start - is this normal? I thought the temperature and load had to come up before it operates? There is no vacuum at idle when warm, which makes more sense to me.
I also noticed that it takes about 3 minutes of driving to get an O2 reading, I thought the heater in the O2 sensor would get it up to temp quicker than this too?

I'm troubleshooting repeated P0403 "EGR Flow Circuit Malfunction" pending trouble codes that coincide with limp mode shortly after a cold start each morning, resolved by restarting.
-I have replaced the EGR solenoid but nothing has changed.
-I have recently also replaced the O2 sensor and the exhaust temp sensor (orange plug).
-The MAP readings appear normal.
-Dealer didn't find any mechanical or electrical issues with the EGR and DPF system

Other possibilities:
-problem with one of the N75 valves - not sure why would be a cold start only issue
-turbo pressure sensor issue giving turbo over/under boost - would expect a relevant error code.
-problem with one of the other two exhaust temp sensors
-slow vacuum leak somewhere - haven't tested lines with a gauge so is the next thing on my list to check, as I note others have had similar issues and a small vacuum leak but not sure if had a similar error code.

If anyone can comment on EGR and O2 functions on their working amarok that would be great!


  • EdwinPEdwinP Forum Slave
    edited October 2018
    Maybe check the fuse easy to rule out. Fuse #13 I think but check the layout in the docs of interest.

    Sent from my SM-G965F using Tapatalk
  • andrewlikeshisrokandrewlikeshisrok Junior Member
    edited October 2018
    Fuse all good, thanks.
    Also, no vacuum leak at valve and no corrosion on EGR circuit board.
  • john79john79 Junior Member
    edited October 2018
    Have you blocked or removed the EGR cooler?
    That code will come up if the flow is restricted below what it requires for emissions.
    you can reset that code but it will come back.
    on a side note once the outside air temp gets over 35deg the EGR isnt commanded as much and it should travel for weeks on short trips without any lights on.

    The only way is a tune if you want to disable the egr.

    Sorry i just read over your whole post again and realised the code is different.
    EGR Flow Circuit insufficient was what i was thinking of
  • john79john79 Junior Member
    edited October 2018
    did a quick google and this is what came up on lots of links
    ross tech
    16787/P0403/001027 - Exhaust Gas Recirculation (EGR) Valve (N18): Malfunction
    Possible Symptoms

    Malfunction Indicator Light (MIL) ON
    Rough Idle Speed and/or Engine stalling
    Loss of Power

    Possible Causes

    Fuse(s) faulty
    Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve (N18) faulty
    Exhaust Gas Recirculation (EGR) Valve (N18) stuck/faulty

    Possible Solutions

    Check Fuse(s)
    Check Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve (N18)
    Check/Replace Exhaust Gas Recirculation (EGR) Valve (N18)
    Check Measuring Value Blocks (MVB)
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