2003 Forester: CEL but no code

M

Mike Bender

Hi all,

About 2.5 weeks/300 miles ago my '03 Forester (US) started showing a
check engine light. I hooked up my OBDII code reader and when I read the
display, there was not code recorded. I thought that maybe there was some
noise in the system, so I used the code reader to clear the CEL, which it
did. Shortly after I started the car the next day, the CEL came back
again with no code recorded. I've started leaving my code reader
connected while I'm driving to see if it can pick up a transient code,
but nothing has been recorded. Some other things to note:

- the car runs great and my fuel mileage is normal

- when I reset the CEL, the I/M readiness monitors were also reset. In
the two weeks or so since then, the oxygen sensor, catalyst and
evaporative system monitors have yet to come ready

- don't know if it matters, but about 6 weeks ago, I had the pistons
replaced under warranty for piston slap. At the same time, they replaced
the cam belt tensioner, cam belt and various seals.

I've done some googling about this, but everything I've found (none of it
Subaru specific) was basically "your computer is fried, buy a new one".
It seems to me that if the computer was actually gone, the car wouldn't
run normally.

Ad<thanx>vance for any assistance...

- Snuffy -
 
Hi all,

About 2.5 weeks/300 miles ago my '03 Forester (US) started showing
a
check engine light. I hooked up my OBDII code reader and when I read the
display, there was not code recorded. I thought that maybe there was
some noise in the system, so I used the code reader to clear the CEL,
which it did. Shortly after I started the car the next day, the CEL came
back again with no code recorded. I've started leaving my code reader
connected while I'm driving to see if it can pick up a transient code,
but nothing has been recorded. Some other things to note:

- the car runs great and my fuel mileage is normal

- when I reset the CEL, the I/M readiness monitors were also reset. In
the two weeks or so since then, the oxygen sensor, catalyst and
evaporative system monitors have yet to come ready

- don't know if it matters, but about 6 weeks ago, I had the pistons
replaced under warranty for piston slap. At the same time, they replaced
the cam belt tensioner, cam belt and various seals.

I've done some googling about this, but everything I've found (none of
it Subaru specific) was basically "your computer is fried, buy a new
one". It seems to me that if the computer was actually gone, the car
wouldn't run normally.

Ad<thanx>vance for any assistance...

- Snuffy -

Anytime there is a code, it should be recorded. Maybe there is something
wrong with your code reader. Hopefully its set to read both active codes
and codes stored in history!?


CL
 
dnoyeB said:
Anytime there is a code, it should be recorded. Maybe there is something
wrong with your code reader. Hopefully its set to read both active codes
and codes stored in history!?


CL

Yep, very curious. Has this reader worked before on your car? Any chance
the reader could be tested on another sube? I THINK, there are 4
protocols for OBDII and the reader must read the ISO/w'ever style to
read a sube. I think a few cheaper readers won't read subes - but then
it seems unlikely it could clear the computer. weird.

I think it takes a number of heat up/cool down drive cycles to acheive
'readiness'. If you drove only short distances, perhaps that's why the
readiness hasn't completed?

Carl
 
Yep, very curious. Has this reader worked before on your car? Any
chance the reader could be tested on another sube? I THINK, there are
4 protocols for OBDII and the reader must read the ISO/w'ever style to
read a sube. I think a few cheaper readers won't read subes - but then
it seems unlikely it could clear the computer. weird.

I think it takes a number of heat up/cool down drive cycles to acheive
'readiness'. If you drove only short distances, perhaps that's why the
readiness hasn't completed?

Carl

Yup, I've used this reader before on my Subaru to diagnose an
intermittent misfire due to a defective coil pack that was eventually
replaced under warranty about 3 years ago. I also use this reader on my
wife's Hyundai with no problems.

The driving I did after I reset the computer was a combination of
city/expressway for about 10 days with most trips being my 20 minute
commute with speeds up to ~60 mph, and some longer trips (about 45-60
minutes) at least one of which was about 20-30 minutes on an interstate.
This kind of a driving pattern in the past has been enough to bring the
monitors to readiness. I'm really puzzled by this and I really don't want
to go visit the wallet-vac at the Subaru dealership. Luckily my emissions
inspection was just last month so I've got nearly a year to figure this
out.

- Snuffy -
 
Mike said:
Yup, I've used this reader before on my Subaru to diagnose an
intermittent misfire due to a defective coil pack that was eventually
replaced under warranty about 3 years ago. I also use this reader on my
wife's Hyundai with no problems.

The driving I did after I reset the computer was a combination of
city/expressway for about 10 days with most trips being my 20 minute
commute with speeds up to ~60 mph, and some longer trips (about 45-60
minutes) at least one of which was about 20-30 minutes on an interstate.
This kind of a driving pattern in the past has been enough to bring the
monitors to readiness. I'm really puzzled by this and I really don't want
to go visit the wallet-vac at the Subaru dealership. Luckily my emissions
inspection was just last month so I've got nearly a year to figure this
out.

- Snuffy -

WEll, I think it may be time to find an Autozone or 'friendly mechanic'
to see if their reader can get a code. I'd say there could be merit to
the 'fried computer' (at least the scanner interface port) IF a
different reader fails in a similar manner.

good luck

Carl
 

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