User's Manual

Gas Analysis
72
High Gas Levels
4 Gas Relationship
Gas Possible cause
High CO EVAP system problem
PCV system problem
Fuel system problem
Control system problem
High HC/CO Fuel system problem
Running rich
Blown head gasket
High HC Mechanical system problem
Electrical system problem
Fuel system problem
Running lean
Warm air intake problem
Cat problem
EVAP system leak
High NOx High combustion pressure
High combustion temperature
High O
2
content
High HC/NOx Cat problem
CO CO
2
HC O
2
Problem
H L H H Rich mixture with ignition misfire
H L H L Faulty thermostat or ECT sensor - rich mixture fault
L L L H Exhaust leak after Cat
L H L H Injector misfire with Cat at operating temperature
H L N H Rich mixture
H H H H Injector misfire, Cat not working - Rich mixture &
vacuum leak
L L H H Ignition misfire; lean mixture; unmetered air leak
L H L L Good combustion efficiency with Cat at operating
temperature