| PIERBURG PRODUCTS | ON-BOARD DIAGNOSTICS |
| 01 EGR coolers | 09 Engine control unit |
| 02 Intake manifold | 10 Malfunction indicator lamp (MIL) |
| 03 Air mass sensor (LMS) | 11 Diagnostic plug |
| 04 Pneumatic EGR valve (petrol) | 12 OBD data scan tool |
| 05 Electric EGR valve (petrol) | |
| 06 Electromotive EGR valve (diesel) | |
| 07 Pneumatic EGR valve (diesel) | |
| 08 Electropneumatic pressure transducer (EPW) for pneumatic EGR valves |
FROM PRACTICAL USE
FINDING AND REMEDYING FAULTS
| DIAGNOSTIC TROUBLE CODE | P0400 | P0401 | P0402 |
| DISPLAYED FAULTS | EGR system – flow malfunction The EGR valve does not open: • There is no exhaust gas recirculation, or it is not detected • Output not reached • Engine goes into limp home function • Driving behaviour is deficient • Uneven idling | EGR system – insufficient flow rate Not enough exhaust gas is being recirculated: • EGR valve does not open wide enough • Cross section restricted by impurities (carbon deposits) • EGR valve opening time too short • Air mass sensor defective or soiled | EGR system – excessive flow rate Too much exhaust gas is being recirculated: • EGR valve opens to an extent that deviates from the set-point values • Valve does not close completely • Air mass sensor defective or soiled |
| NEXT STEPS/ POSSIBLE REMEDIES | • Check pneumatic EGR valve with vacuum hand pump: If the vacuum is not maintained, replace the EGR valve; check the vacuum lines for free flow/ tightness • Examine the EGR valve for visible damage or discolouration: - Exhaust gas back pressure could be too high or the actuation could be incorrect - Check the exhaust system for free flow • If there is sticking, replace the EGR valve and check the fuel injection system and the oil vapour separator (blow-by separator) • Check the power supply to the EGR valve and electropneumatic pressure transducer | • Check electric actuators • Check pneumatic actuators (vacuum) • If there is sticking, replace the EGR valve and check the fuel injection system and the oil vapour separator (blow-by separator) • Especially for electric EGR valves, check actuators and sensors • Check the air mass sensor and replace if necessary | • Check sensors and actuators • If there is sticking, replace the EGR valve and check the fuel injection system and the oil vapour separator (blow-by separator) • Check the air mass sensor and replace if necessary |
| DIAGNOSTIC TROUBLE CODE | P0403 | P0404 | P0405 - P0408 |
| DISPLAYED FAULTS | EGR system – control loop malfunction EGR signals incorrect or implausible: • Wear/soiling of the potentiometer in the EGR valve, temperature sensor | EGR System – control loop measurement/power problem • Exhaust gas recirculation outside set-point range • EGR signals incorrect or implausible • Wear/soiling of potentiometer in the EGR valve, pressure sensor, temperature sensor, air mass sensor, electrical plug-in connections and lines | EGR system – sensor A/B circuit too small/large • EGR signals incorrect or implausible • Wear/soiling of potentiometer in the EGR valve, pressure sensor, temperature sensor, air mass sensor, electrical plug-in connections and lines |
| NEXT STEPS/ POSSIBLE REMEDIES | • Check signals and compare with set-point values | • Check signals and compare with set-point values • Check lines, plug-in connections and components | • Check signals and compare with set-point values • Check lines, plug-in connections and components |