Please help with 2 scan codes

H

HyperMPG

Active member
Joined
Mar 18, 2009
Location
Fayston, Vermont
TDI
2002 Jetta TDI 5 Speed
Greetings from Vermont.
My 2002 Jetta tdi developed a rough start and idle when cold. Scan code said:
P0101 MAF or VAF A Circuit Range/ Performance
And
P0402 P EGR Flow Excessive

Can anyone suggest a plan of attack in repairing the offending component?
I would like to fix it myself if I can get a proper translation of these 2 codes.
Thanks in advance.
 
flee

flee

Veteran Member
Joined
Sep 19, 2011
Location
Chatsworth, CA
TDI
2002 Jetta GLS wagon
Visually inspect the EGR/ASV linkage and vacuum hoses. Is the EGR leaking any oil?
Try unplugging the MAF and see if that improves how it runs.
 
H

HyperMPG

Active member
Joined
Mar 18, 2009
Location
Fayston, Vermont
TDI
2002 Jetta TDI 5 Speed
Thanks Flee,
Schooling myself on EGR valves.
Will check on your suggestions.
Have only 62 K miles on my 2002 but a lot of short winter trips.
Maybe time for a EGR soot cleanout.
 
BobnOH

BobnOH

not-a-mechanic
Joined
May 29, 2004
Location
central Ohio
TDI
New Beetle 2003 manual
Some help over here, search codes-
Ross-Tech
The simple MAF code is pretty tricky, sometimes is just bad, sometimes other factors are throwing off readings. Check wiring/connects in the area.
A bit of oily leakage near the EGR is fairly normal.
 
Last edited:
Tdijarhead

Tdijarhead

Top Post Dawg
Joined
Nov 10, 2013
Location
Lawrenceville PA
TDI
2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
Ross-tech.com Wiki and then their fault code page.


16485/P0101/000257


Contents







16485/P0101/000257 - Mass Air Flow Sensor (G70): Implausible Signal

Possible Symptoms


  • Loss of Power
  • Erratic Idle
Possible Causes


  • Mass Air Flow Sensor (G70) faulty
  • Air Leak(s) after Mass Air Flow Sensor (G70)
  • Excessive restrictions in the Intake/Exhaust System
    • Dirty air filter, clogged snow screen, clogged CAT
  • Ground Spots corroded or Paint Residue
  • Wiring and/or Connections from/to Mass Air Flow Sensor (G70) faulty
Possible Solutions


  • Check Intake Air Filter
  • Check Mass Air Flow Sensor (G70)
  • Check Ground Spots
  • Check Wiring and/or Connections from/to Mass Air Flow Sensor (G70)
Special Notes


  • In MY 1995-2002 (?) in Europe at VW-diesel-cars G70 had the bad reputation of slowly losing his performance, causing loss of power. It's not a matter of defective or breaking down, but it is filthy / dirty (not easy to clean). You can check functionality by making a log in [01-engine], [meas.blocks-08], group 003 (3e gear, full throttle, from 1700-4000rpm)
  • It is not uncommon for a TDI to set Implausible Signal Mass Air Flow Sensor (G70) faults when the engine performance is reduced due to a mechanical problem. These mechanical problems may include, but are not limited to:


16786/P0402/001026


Contents







16786/P0402/001026 - Exhaust Gas Recirculation (EGR): Excessive Flow

Possible Symptoms


  • Malfunction Indicator Light (MIL) ON
  • Reduced Exhaust Gas Recirculation (EGR)
  • Reduced Power Output/Engine running rough
  • Increased Emissions
Possible Causes


  • Exhaust Gas Recirculation (EGR) Valve stuck open/leaking/faulty
  • Exhaust Gas Recirculation (EGR) System leaking/faulty
  • Wiring and/or Connector(s) from/to Exhaust Gas Recirculation (EGR) Valve faulty
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
 
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