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3491

OBD and Air Supply

Pierburg | Motorservice

The diagnostic trouble codes P0097, P0102, P0400, P0172 and P0506 can be displayed on an on-board diagnostic system (OBD). They indicate a fault within the air supply system of the vehicle. You can find out the causes of these diagnostic trouble codes and what you can do to resolve the issue here. 

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PIERBURG PRODUCTS ON-BOARD DIAGNOSTICS
01 Activated carbon filter valve 12 Engine control unit
02 EGR valve 13 Malfunction indicator lamp (MIL)
03 Electric drive module 14 Diagnostic plug
04 Intake manifold/variable intake manifold 15 OBD data scan tool
05 Intake manifold pressure sensor
06 Throttle valve/regulating throttle
07 Air mass sensor (LMS)
08 Recirculating air valve
09 Pressure transducer (for actuating the VTG turbocharger)
10 Air filter (Kolbenschmidt)
11 Idle controller

FROM PRACTICAL USE

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Deposits on swirl flaps
3494
Soiled air mass sensor
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Stuck throttle valve

FINDING AND REMEDYING FAULTS

DIAGNOSTIC TROUBLE CODE P0097 P0102, P0400
DISPLAYED FAULTS Intake air temperature sensor – input signal too low
• Plausibility check delivers incorrect reference values
• Temperature sensor on air mass sensor is defective
• Intake air temperature sensor faulty
Mass air flow meter or air flow meter – input signal too
low/exhaust gas recirculation – flow rate malfunction
• Air mass sensor faulty
• Stuck/carbonised EGR valve is always open
• Basic setting of EGR valve not performed
NEXT STEPS/ POSSIBLE REMEDIES • Check air mass sensor, replace if defective
• Check intake air temperature sensor, replace if
necessary
• Check power supply to mass air flow meter and EGR valve
• Check mass air flow meter, replace if defective
• Check EGR valve:
- If the EGR valve is always open, exhaust gas is recirculated
permanently
- If the EGR valve is stuck, replace and find out the
causes of the sticking
• Once a new EGR valve has been installed: perform
basic setting (engine tester)
DIAGNOSTIC TROUBLE CODE P0172 P0506
DISPLAYED FAULTS Mixture too rich
• Activated carbon filter solenoid valve stuck (permanently
open):
Fuel-enriched air from the activated carbon filter is
drawn into the intake air system
• Diaphragm of the pneumatic fuel pressure regulator
leaking: Fuel is drawn into the intake air system
through the vacuum line
• Stuck/carbonised EGR valve is always open
Idle control – engine speed below set-point value
• Idle controller soiled/stuck
• Incorrect input signals arriving from the engine control
unit
• Throttle valve stiff/stuck
NEXT STEPS/ POSSIBLE REMEDIES • Activated carbon filter solenoid valve, replace if
necessary
• Check fuel pressure regulator, replace if necessary
• Check EGR valve:
- If the EGR valve is always open, exhaust gas is recirculated
permanently
- If the EGR valve is stuck, replace and find out the
causes of the sticking
• Check idle controller using an oscilloscope
• Replace stuck/carbonised idle controller
• Read out input signals of the idle controller using the
diagnostic tester
• Replace stuck/carbonised throttle valve and find out
the causes of the sticking

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