TechnicalInstructions LMVSeries
DocumentNo.LV5‐1000
Section7 Page14 SCCInc.
O2SensorReadingGrosslyHighorLow
IftheO
2
readingsfromtheO
2
sensoraregrosslyhighorlow,checkthefollowing:
1. Themilli‐voltsignalsfromtheQGO20tothePLL52couldhaveinterference.Ensurethatthe
highandlowvoltagewiresthatrunfromtheQGO20tothePLL52areinaseparateconduit.
2. TheQGO20sensorreads%O
2
wet.Mostcombustionanalyzersread%O
2
dry,sotheO
2
numbershownontheAZL52istypicallyatleast1%O
2
lowerthanthecombustionanalyzer.
3. TheQGO20sensormaybemountedincorrectly,andthesensorisnotpickingupa
representativereadingofthe%O
2
inthestack.
O2SensorReadsButRespondsVerySlowly
Ifthe%O
2
beingdisplayedisrespondingslowlytocombustionchanges,checkthefollowing:
1. EnsurethattheQGO20sensorisclean.Thiscanbedonebyshuttingoffthe powertothe
LMV52,andremovingtheQGO20fromthestack.Becarefulasthesensorislikelytobevery
hot.AftertheQGO20isremovedfromthestack,letitcoolforatleastanhour.
Afterthesensorhascooled,itcanbeblownoutusinglowpressurecompressedair(less
than15PSIG)throughthetopofthesensorandoutthefront.Ifthisisdonewhenthe
QGO20sensorishot,theceramicsinsidethesensorwillmostlikelybecrackedandthe
sensorwillneedtobereplaced.
2. ChecktheorientationoftheQGO20sensorandtheAGO20collector.Theonenotchonthe
AGO20collector’sflangeshouldbebetweenthetwonotchesontheQGO20sensor’sflange.
Also,ensurethatthebevelofthecollectorispointedintotheflowofthestackgas.
3. Checktheinternalresistance
oftheQGO20sensorusingthefollowingmenupath:
Params&Display>O2Module>ProcessData>QGOResistance
Thisvalueincreasesasthesensorages.Astheinternalresistanceincreases,theresponse
timeofthesensoralsoincreases.
Anewsensorhas0Ohms,whilethemaximumresistance
is150Ohms,indicatingreplacementofthesensorisnecessary.