Dodge Sprinter 2006 Manual page 1722

14 - 46 FUEL INJECTION
1 - EXHAUST PIPE
2 - EXHAUST GAS FLOW
3 - O2 SENSOR CONNECTOR
4 - TRIMMING RESISTOR
5 - GAS SAMPLE CHAMBER
At h igh t em per a t u r es, cer t a in cer a m ic m a t er ia ls,
su ch a s zir con iu m -dioxide (Zr O2) becom e oxygen ion
con du ct or s. In a t ypica l O2 sen sor, t h e Zr O2 is u sed
a s a solid elect r olyt e, wh ich con du ct s oxygen ion s.
Th e solid elect r olyt e is sa n dwich ed bet ween t wo pla t -
in u m elect r odes. Th e sen sor gen er a t es a sm a ll volt -
a ge wh en oxygen m oves fr om t h e h igh con cen t r a t ion
side t o t h e low con cen t r a t ion side.
Th e sa m e h old t r u e if t h e pr ocess is r ever sed. If
volt a ge is a pplied t o t h e pla t in u m elect r odes, oxygen
ca n be pu m ped fr om on e side of t h e solid elect r olyt e
t o t h e ot h er (fr om ca t h ode t o a n ode), becom in g a n
oxygen pu m p. Th e a m ou n t of cu r r en t flow is dir ect ly
pr opor t ion a l t o t h e a m ou n t of oxygen pu m ped by t h e
sen sor. Wh en t h e oxygen level on t h e su pply side
r ea ch es zer o, t h e cu r r en t st ops.
Th e E CM a ct iva t es t h e in t egr a l h ea t er elem en t t o
r a ise t h e t em per a t u r e of t h e sen sor t o 700C (192°F )
for t h e Zr O2 t o becom e con du ct ive. Th e h ea t er ele-
m en t is design ed t o r ea ch t h is t em per a t u r e wit h in 8
Fig. 25 O2 CONSTRUCTION
6 - REFERENCE AIR CHANNEL
7 - HEATER ELEMENT
8 - SENSOR CELL
9 - OXYGEN PUMP CELL
10 - SAMPLE PASSAGE
secon ds a n d m a in t a in in g it a t t h is level. In cold t em -
per a t u r es, t h is ca n be dela yed u p t o 5 m in u t es t o
pr even t da m a gin g t h e cer a m ic coa t in g of t h e sen sor
fr om wa t er con den sa t ion . On ce t h e sen sor is h ea t ed,
t h e exh a u st ga s com pon en t s diffu se t h r ou gh t h e ga s
sa m ple ch a m ber. Upon r ea ch in g t h e elect r odes on t h e
oxygen pu m p a n d con cen t r a t ion cells t h ey r ea ch st a t e
of t h er m odyn a m ic ba la n ce (F ig. 26).
VA