OBD and Air Supply

Information on diagnostics

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.

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

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