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1998 saturn 1.9 liter 4 has evap loss keep coming up in ...
Sent to Car Experts June 28 01:49 PM

1998 saturn 1.9 liter 4 has evap loss keep coming up in the codes and engine light keeps going off and on ??? I pressurized the fuel tank and filler neck and no leaks cap was replaced also any answers Thanks jerrry

 

Optional Information:
1998 Saturn 1.9

Already Tried:
Replaced gas cap reset codes few times but evetually comes back on again pressurized tank and filler neck no leaks on it either.... thanks jerry

Customer (name blocked for privacy)
Status:  Closed   Value: $9
Info Request
June 28 2:01 PM (11 minutes and 53 seconds later)
         

Customer (name blocked for privacy),

What EVAP code keeps setting? Is this the single or dual overhead cam engine?

 

 

 

Shawn

Picture
LSx Tech Shawn -- Auto Service Technician -- 100% Positive Feedback on 422 Car Accepts
State certified emissions and inspection tech.
Reply
June 28 2:22 PM (20 minutes and 29 seconds later)
         
0446 Twin cam 16 valve vent control system thanks jerry
Customer (name blocked for privacy)
Answer
June 28 2:46 PM (24 minutes and 39 seconds later)
         
ACCEPTEDCheck Mark

carpartj,

This is for a blocked EVAP canister vent. The system can still hold pressure and set the code. It could be a bad vent solenoid, wiring to the solenoid, bad PCM or carbon buildup in the vent solenoid. Here is the diagnostic procedure for test the circuit for this code. Some of it you will need a scan tool that allows commanding of the solenoid on and off and some testing can be done with a test light. Check the vent valve for carbon buildup blockage along with the line going to it. More than likely the valve is bad or blocked with carbon.

Vent valve should be on the fuel filler neck.


TESTS W/CODES -1998 Saturn SC2 Page 1 of 2

 


DTC P0446 - EVAP SYSTEM CANISTER VENT BLOCKED

NOTE: For circuit reference, see WIRING DIAGRAMS article.


Circuit Description

The EVAP system is tested with on-board diagnostics by applying
pressure (vacuum) to the system and monitoring pressure change. PCM
monitors vacuum level at fuel tank vapor pressure sensor. At
appropriate time, the EVAP vent solenoid is commanded closed
(normally open) and EVAP canister purge valve is commanded to a
fixed duty cycle, allowing engine to draw vacuum on the entire
evaporative emission system.

After a calibrated vacuum level is achieved, EVAP canister purge
valve is turned off, sealing the system. A restricted or blocked
EVAP canister path is detected by opening or releasing the vent
solenoid and monitoring for a rapid change in pressure from the
pressure sensor. With EVAP vent solenoid open, any vacuum in the
system should release rapidly unless path is blocked. A blockage can
be caused by the following conditions:

lFaulty EVAP vent solenoid.
lPlugged, kinked or pinched vent hose.
lShorted EVAP vent solenoid driver circuit (should set P0449).
lPlugged EVAP canister.

Conditions for setting this DTC:

lDTCs P0106, P0107, P0108, P0112, P0113, P0117, P0118, P0121,
P0122, P0123, P0125, P0131, P0133, P0134 and P1144 are not set.
lBARO is greater than 80.8 kPa.
lBoth ECT and IAT 14-122°F (10-50°C) at engine start-up.
lECT and IAT are within 10 degrees of each other at start-up.
lFuel tank level 15-85 percent.
lEngine run time is greater than 2 seconds.
lTP sensor 9-35 percent.
lEVAP canister purge solenoid is at 50 percent PWM with 60
seconds of start engine run time.
lEVAP system is unable to release vacuum when diagnostic test is
run.


Diagnostic Procedures

1.Connect scan tool. Turn ignition on, engine off. Using scan tool, view malfunction history DTCs. If DTC P0443 or P0449 is
present, diagnose affected DTC. If DTCs are not present, go to
next step.
2.Using scan tool, command both the canister purge solenoid and
EVAP vent solenoid on and off. If both solenoids click when
commanded on and off, go to next step. If either or both
solenoids does not click when commanded on and off, go to step
4).
3.Using scan tool, run SERVICE BAY test. If test indicates PASS,
problem is intermittent. See DIAGNOSTIC AIDS. If test does not
indicate PASS, check for a kinked or pinched vent solenoid hose.
Repair as necessary. If hose is okay, replace vent solenoid.
4.Disconnect harness connector to affected solenoid. Using a test
light, connect test light between harness connector terminals.
Turn ignition on, engine off. If test light does not illuminate,
go to next step. If test light illuminates, check control
circuit for short to ground. Repair as necessary. If circuit is
okay, replace faulty PCM.
5.Using scan tool, command solenoid on. If test light illuminates,
replace solenoid. If test light does not illuminate, connect
test light between ground and source circuit. If test light does
not illuminate, repair open in source circuit. If test light
illuminates, check for open in control circuit or faulty
terminal connection. Repair as necessary. If circuit or terminal
connection is okay, replace PCM.


Diagnostic Aids

Check for missing or leaking "O" rings at fuel vapor line
connections or fuel sender. Check for cracked or damaged EVAP
canister. Check for damaged source vacuum line, EVAP purge line,
EVAP vent hose or fuel tank vapor line. Check for poor connections
at PCM. Use EVAP pressure/purge diagnostic station and ultrasound
leak detector to locate leak.


 

 

 

 

 

Shawn

Picture
LSx Tech Shawn -- Auto Service Technician -- 100% Positive Feedback on 422 Car Accepts
State certified emissions and inspection tech.
Reply
June 28 3:04 PM (17 minutes and 3 seconds later)
         
Is the vent solenoid located in the wheel well compartment of the rear drivers side well with a hose going to it and a two wire plug connector I dont see anything on the fuel filler neck itself
Customer (name blocked for privacy)
Answer
June 28 3:17 PM (13 minutes and 47 seconds later)
         
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State certified emissions and inspection tech.
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