© MS Motor Service International GmbH – 05/05 EN K MS Motor Service International GmbH·74196 Neuenstadt ·Germany www.ms-motor-service.com * The reference numbers given are for comparison purposes only andmust not beused oninvoices to theconsumer. The right of changes anddeviating pictures is Assignment reserved. andusage, refer to theeach case current catalogues, TecDoc CDrespectively systems based on TecDoc. Heat film-mass sensor (earlier models) rate andairspeed are very high. burden dueto thefact that bothairflow sensor is subjected to particularly high In thecase of turbo diesels theair mass false information to othercomponents. central control unit, which inturn sends deliver false input signals to theengine's A defective airmass ordirty sensor can reduction of exhaust andairsupply. It is animportant component inboththe of exhaust. engines -also to control therecirculation fuel injection and-inthecase of diesel sensor is used to calculate theamount of The signal produced by theairmass mass”) with great precision. of airinducted by theengine (“airflow The airmass sensor measures themass Applications Troubleshooting, defects andtesting Air mass sensors olbenschmidt Audi, F Mercedes Benz Vehicle rectifier flow ord, Seat, Skoda, VW temperature sensor P ierburg

G rou p electronic unit heat film sensor

7.22684.08.0 7.22684.07.0 Pierburg No. Product nal to the amount of airinduced. This heating current is directly- proportio via theelectronic controller unit. down is compensated by aheating current cools theheat-film sensor. This cooling- vehicle manufacturer). The inflow of air induction temperature (depending on perature of approx. 120°C -180°C above The heat-film sensor is heated to a tem- apply. case theburn-through procedure does not heating resistor inwhich onasupport, Newer models work using afilm-like engine. increaseshort inheat afterturning offthe “burned free” by polluants following the wire sensor element. The hot-wire was Earlier models were fitted with ahot- sensor. ced air-flow is directed past theactual a flow channel (“pipe”)inwhich theindu- The complete airmass sensor consists of Description offunctions “air mass sensor”. versions (with tube/separate) are termed separate individual plugin module. Both material, orwith theactual sensor as a integrated inatube made of synthetic the airmass sensor is eithercompletely Depending on the typeof use and vehicle, F00C 2G2004 F00C 2G2056 7.22684.00.0 Replacement for Air mass sensor F or technical personnel only! (newer version, exploded view) Heat f ilm-air mass sensor Construction types tions andback-flow. bridges are also able to recognize pulsa- Newer models with 2seperate measuring sity of theairpassing by. This methodtakes into account theden- 06A 906461;028461 611 0940048;A0048 O.E. No.* electronic unit sensors SI 0079 Page 1/4

SERVICE Information © MS Motor Service International GmbH – 05/05 EN K MS Motor Service International GmbH·74196 Neuenstadt ·Germany www.ms-motor-service.com • • • consequences: faulty signals. This can have thefollowing Defects airmass anddirty sensors deliver Defects andpossible causes Clogged air mass sensor olbenschmidt minimal operation power shortage black smoke P ierburg

G rou p • • Possible causes ofdamage: sensor. ventilator can lead to fouling-up of the Excessive oil spray from thecrankcase sensitive sensor element. with theairmass sensor, destroying the inducted air These collide at highspeed particles can findtheirway into the If theairintake tube is porous, dirt F or technical personnel only! • • • • mass sensor to deliver afalse signal: Other sources can also cause anintact air • • • Oil spray on the heat-film sensor clogged airfilters porosity of inductiontract defectivefueltank ventilation valves valves defective exhaust-gas recirculation sensor. air filters can damage ordirt-clogthe Oil particles from oil-covered sport effect. gritting andmelting snow increases this the sensor. Salt water caused by winter clean-air side anddamage ordirt-clog heavy rainfall, can force its way into the Splashed water, for instance from mass sensor. the cause of anddamage dirt to theair wrong orsubstandard airfilters can be ness whenchanging airfilters, use of Bad servicing, for instance uncleanli- SI 0079 Page 2/4 © MS Motor Service International GmbH – 05/05 EN K MS Motor Service International GmbH·74196 Neuenstadt ·Germany www.ms-motor-service.com Frames”. ment are captured andstored as “Freeze ting to operation andoperating environ- In addition to theerror, data further rela- firmed) and stored as anOBDerror. error is thenreferred to as “defined” (con- cycle orwithin acertain timeinterval. This same error occurs during thenext driving Warning-lamps are not activated until the the warning-lamp will not light up. this is stored as an“undefined error” but cycle that would influence the exhaust, If anerror is detected during thedriving result inawarning-lamp lighting up. Not everyfault detected by theOBDwill Sporadic errors defective airmass sensor: show here can also beindicative of a For this reason theerror messages we engine's central electronic control unit. information to othercomponents by the sensor can result indeliveryof false Wrong signals from adefective airmass codes: These are someof thepossible error Board Diagnosis (“OBD”). Air mass sensors are monitored by On- (“OBD”) Air mass sensors andOn-Board Diagnosis olbenschmidt P ierburg

G rou p Emission control &OBD”. brochure “Service Tips &Infos – reading of error codes can befound inour F • • • a reading device (“Scan Tool”): a motor-tester or vehicle’s diagnostic (interface) port using Stored data can beaccessed from the certain time-frame. if anerror does not reoccur within a The warning-lamp may also extinguish urther informationurther about OBDandthe P0402 P0401 P0175 P0172 P0171 P0104 P0103 P0102 P0101 P0100 . . . which anerror occurred, inmode2 operational data (“FreezeFrames”), in sporadic errors inmode7 confirmed (defined)errors inmode3 AGR-System –flow-rate too high AGR-System –flow-rate too low Mixture control (Bench 2)system too rich Mixture control (Bench 1)system too rich Mixture control (Bench 1)system too lean Air mass- orairflow meter circuit interruptions Air mass- orairflow meter circuit too large Air mass- orairflow meter circuit too small Air mass- orairflow meter range orperformance problem Air mass- orairflow meter circuit malfunction . . . F or technical personnel only! sensor should have priority. testing of thealready installed airmass Before installing anewairmass sensor, previously-described cases. and theirorigins can befound inthe The reason for these sporadic errors as anerror. and this will beinterpreted by theOBD produce anincorrect measuring result, Dampness, oil spray, orprotection often rily mean that thesensor is defective. air mass sensor, this does not necessa- If theOBDdisplays asporadic error inthe SI 0079 Page 3/4 © MS Motor Service International GmbH – 05/05 EN K MS Motor Service International GmbH·74196 Neuenstadt ·Germany www.ms-motor-service.com SI 0017/A. can befound inService Information 7.18221.51.0 (replaces 7.18221.01.0) Details of how to test the air mass sensor methods. have to betraced using suitable testing ponent itself are prestored as errors. They faults inthewire harness orinthecom- In most areas of application, electrical or error. recognise theactual cause of malfunction defective function, but will not necessarily The OBDwill recognise adefective partor Please note that: motor-tester orscan tool. first step is to read theerror code using a When making anerror diagnosis, the Testing olbenschmidt ! ! 5 4 3 2 1 Connector assignment UA (output signal) reference voltage U ground vehicle supply voltage U TF (option) destroy thesensor. with compressed air. This can Never clean theairmass sensor nents. can destroy electronic compo- tors. The ensuing power spikes connect any oftheplug connec make sure notto disconnect or If theignitionis switched on, P ierburg

G rou Ref p Bat - oscilloscope. oscilloscope. Testing can bedoneusing a voltmeter or contacts occasionally checked over. cked for short-circuits, andthegaps and wiring andplugs involved should beche- If these voltage levels are not reached, all • • assignment): be there (seeillustration: Connector The following electrical potential should • • clamp onto thewiring! using suitable test pods. Take care not to nected to theclamps (rear side of plug) the measuring instrument should becon- If nospecial test cable is available then • • • Checking current potential in various ways: Testing of theairmass sensor can bedone German exhaust emission test. Note: AU (Abgasuntersuchung) = • • • requirements: Testing thelow endofthe sensor curve 5 Volt(sensorvoltage). between pin4and3: 12 Volt (vehicle supply voltage). between pin2and vehicle ground: pin 3. the output voltage between pin5and With theengine switched off, measure Turn ontheignition. Measure current ontheplug. Turn ontheignition. Pull theplug from theairmass sensor. figures. Minimum RPMare reached based onAU Air filter is clean. AGR system is functioning properly. F or technical personnel only! replaced. rance level, theairmass sensor should be If theoutput voltage lies outside this tole- shielded. the measuring tube should besuitably by aircurrents (wind), thenbothends of If there is arisk of false results caused correctly. mass sensor is almost always functioning when aircurrent is zero, thentheair If theoutput voltage is 1.00+/-0.02 Volt must bereplaced. If this is not thecase, theairmass sensor • between idle and fullthrottle. measurement from about 1.0to 4.4 Volt The airmass sensor delivers voltage- • Measurement ofworking resistance is defective andmust bereplaced. If this does not happen, thenthesensor corresponding to theamount blown in. The output voltage level should now rise, • Testing reaction reached. between 3.8and4.4 Volt must be by using theaccelerator. Signal voltage Increase theRPMto governed speed neutral gear): 1.2-1.6 Volt. control (set-) point (with warm engine in Turn ontheengine. gently into theairmass sensor. When the1-Volt level is reached, blow SI 0079 Page 4/4