Honda Civic Service Manual page 526

Emission Control System
Exhaust Gas Recirculation (EGR) System (D16Y5 engine with GWI (cont'dl
lTl49il
T_he scan tool indicates Diagnostic Trouble Code (OTC) P1491: A malfunction in the Exhaust Gas Recirculation
-
l E g h ) s v s t e m .
CvT lM/T see page 1l-2611:
J
EGR VALVE
LIFT SENSOR #16 HOSE
PUMP/GAUGE,0- 30 in.Hs
A 9 7 3 X - 0 4 1 - X X X X X
EGR
VALVE
The MIL has been reoorted on.
DTC P1491 is stoled.
Problem verification:
1. Do the ECM/PCM Reset Proce-
du re.
2. Connect the SCS service con'
3 . S t a r t t h e e n g i n e . H o l d t h e
engine at 3,000 rpm with no
load {in Park or neutral) until
the radiator fan comes on,
4. Drive the vehicle on the road
for approx. 10 minutes. Try to
keep the engine speed in the
1,700 - 2,500 rpm range.
Intermittonl failure, system is OK
at this time. Check for Door con-
nections or loose wires at, C144
{EGR velve} and ECM/PCM.
l s D T C P l 4 9 l i n d i c a t e d ?
C h e c k f o . v a c u u m t o i h e E G R
1. Disconnect the No. 16 hose from
t h e E G R v a l v e .
2 . C o n n e c t a v a c u u m p u m p /
g a u g e t o t h e h o s e .
3 . S t a r t t h e e n g i n e a n d l e t i t i d l e .
ls there any vacuum?
C h e c k t o r a m a l f u n c t i o n i n t h e
EGR control solenoid valve:
' 1 .
D i s c o n n e c t t h e E G R c o n t r o l
solenoid valve 2P connector,
2 . B e c h e c k t h e N o . 1 6 h o s e f o r
Check vacuum hose routing o,
the entire EGR svstem. lf hose
routing is OK, replac€ the EGR
control solenoidvalv6.
l s t h e r e a n y v a c u u m ?
Substitute a known-good ECM/
P C M a n d r e c h e c k . I t s y m p t o m /
i n d i c a l i o n g o e s a w a y , r e p l a c e
the original ECM/PCM.
(To page 11 257)
11-256