Error code P0401

[cabledeck]

Hi Folks. My 2010 golf Mk 6 1.6 tdi estate has thrown up the error code P0401.".Exhaust gas circulation insufficient detected". It has happened on three occasions on my last three trips to Leeds, twice if you believe me in the same spot on the Malton byepass. It seems to happen when I accelerate quite hard. The engine management light has never come on when I am driving "normally" locally. On two of the occasions I had added a diesel additive in the tank of diesel in use and I thought it might be connected to that, but this last time, well the additive will have been diluted some time ago. The car is driving really well and I get good mpg. Have any of you had similar problems with this code. Cheers. Bob

[Guest 2]

Going by Rosstech it just needs a wee clean/de-gunk - 16785/P0401/001025 - Ross-Tech Wiki

[towcestervag]

good luck mate
this is a common fault and its usually the valve goosed
its a bitch to remove and clean

[Keithuk]

VAG Error Code: 16785
EOBD II Error Code: P0401

Fault Location:
Exhaust Gas Recirculation (EGR) System - Insufficient Flow Detected

Possible Cause:
Malfunction Indicator Lamp (MIL)(K83) active.
Reduced Exhaust Gas Recirculation (EGR).
Reduced Power Output/Engine running rough.
Increased Emissions.
Possible engine hesitation.

Hose leak/blockage.
Basic setting not carried out.
Exhaust Gas Recirculation (EGR) Flow restricted/clogged.
Exhaust Gas Recirculation (EGR) Valve stuck closed/leaking/faulty.
Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve faulty.
Exhaust Gas Recirculation (EGR) System faulty.
Dead (Weak) battery.
Exhaust gas leaks.

Possible Solutions:
Check/Clean Exhaust Gas Recirculation (EGR) System.
Check/Replace Exhaust Gas Recirculation (EGR) Valve.
Check Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve.
Control deviation < limit from map f (engine speed, desired airflow).

Tech Notes:
Exhaust Gas Recirculation (EGR) flow malfunction could be caused by a clogged Exhaust Gas Recirculation (EGR) valve or Exhaust Gas Recirculation (EGR) tube. Before replacing any parts try cleaning the Exhaust Gas Recirculation (EGR) valve, tube and passages.

When is the code detected?:
Low Exhaust Gas Recirculation (EGR) flow control is detected.

As taken from my EOBD II Fault Codes Software

[cabledeck]

Thanks for the replies chaps. I thought it could be something to do with the egr valve. I wonder if the fuel addive/system cleaner has started this off. Is it a doable job in the drive on ramps, are there major bits to remove. towcestervag, it sounds like you have done the job, what was the most difficult part. Car runs well, the only thing I can think of is a slight hesitation when going over the brow of a hill ie hump back bridge etc, but reading elswhere this is not an uncommon problem I am pretty good with spanners, having repaired diggers and other plant many years ago. Maybe not as mobile as I used to be. Many thanks for your time in replying. Bob