99 Legacy CEL codes Help Please

[30legacyl]

Hey everybody!

Just got back from AAMCO where they pulled the codes on my 2.2L 5spd. SDN. CEL has been off and on recently, has stayed on for the last few weeks. Also recognized we're getting 18-20 mpg on a car that used to get 28-34mpg highway. Supposed to take long trip soon, and I wanna fix whatever's screwing up the car.

AAMCO pulled the following:

P0420 - Catalyst Effeciency below threshold Bank #1

P1133- Undocumented

P1507(1517/1567?)- Undocumented (hard to read their writing)

P0436- Fuel Level Sensor Signal High Input

Stopped @ the dealer, they looked up & called back w/:

P1133- A/F RAtio Sensor High Signal

P1507 (or other)- Idle Air Control Failsafe

 

We've owned the car since new, had full service/tuneup @ 83K by Dealer.

Car now has 153k & new irridium plugs. We knew the gas guage was erratic, just relying on the trip odometer.

 

So... My questions are:

1.) What do these codes mean in terms of what MUST be replaced?

2.) Which of these specifically is causing the rich/ failsafe limp mode & horrible gas mileage? (Car once in a while stumbles/ stutters @ startup but seems to run as well as it always has, just poor mileage.)

3. ) What do I need to do, just replace the front A/F sensor?

4.) How do I reset the computer CEL w/out an OBDII codereader?

 

Thanks for any help! My wife, infant & I appreciate any advice you can give!!

 

Mike- from the Poconos

99 Legacy L Sedan

2.2L 5spd., 30th Anniv. Ed.

w/ 2002 WRX wheels & Tires

[Hiroki]

420 code = usually means your O2 sensor or cat is going bad.

 

however, there have been stories of people using Bosch plugs instead of NGK's and getting that problem. So maybe change your plugs first, cheaper if it is 10$ plugs giving you hell instead of a 200$ OEM O2 sensor. I forget when O2 sensors are supposed to be replaced but if you're stillin using original sensors at 150k, it maybe about time.

 

P0436 - Does OBDII detect failing gauges? I didnt know that.

 

P1133 and 1507 can be problems associated with a failing O2. Solve the 420 problem first before you try to tackle these. Actually, it would seem that most if not all of those CEL's are bad O2 sensor related. As a rule of thumb, the lower the number, the bigger the problem. Your 420 problem can be the cause of most of the others.

 

Good luck

[30legacyl]

Hello again. We just returned from the trip.

Car got erratic mileage, varied from 19.2 to 29.1 MPG, even with the FULL car and a Yakina Rocketbox on top!

 

I know the OBDII can't diagnose bad fuel guage/sender, just listed it as that was how we judged when to get gas when the mileage was more stable!

 

A couple more pieces of the puzzle:

1. This is a California Emissions Car!

2. Yes, it did have Bosch Platinum 4 plugs for at least 30K

3. Now has Irridium NGK's for last 5K

4. Put 2K on it over the trip, mileage was in mid to upper 20's w/ air for approx 80% of trip

5. disconnected battery 3x to try to reset computer trouble codes- no luck re lit Check Engine on startup w/o giving any throttle

6. car seems to run fine (performance wise), just CEL light is on full time

 

Took the AAMCO & Subaru codes to Several parts suppliers

while in upstate South Carolina.

Most stated the same thing you did- bad signal from 'upstream' (front) O2 sensor. Advance Auto sold me a "Universal" fit that it said was a match for this car-

climbed under & Pulled the front O2- four wire square connector, replacement part had 3 wire triangular connector. Looked like BOTH upstream and downstream O2's had 4-wire. None of the parts places seemed to list anything different from the 3-wire Advanced sold me and took back.

Best advice they gave was-"We don't know, you'll probably have to have the dealer supply you or fix it for you."

 

Does anyone know if the front & rear O2's are the same on a 99 Legacy 2.2

WITH CALIF. EMISSIONS?

 

Thanks for the insight before

Any suggestions?

[30legacyl]

any thoughts guys?

[SLegacy99]

You got me. But at least you got those pesky Bosch plugs outta there.

[petridish38]

I just ordered a Denso o2 sensor from sparkplugs.com for my 99 impreza 2.2L california emissions car. I ordered the one that they list for the rear, to put in my front. i am getting a code P1133 as well. I will let you know how that works when it comes in.

 

It seems that non-california imprezas have a 3 wire in the front and a 4 wire in the back. California models have a 4 wire sensor on both the front and back. Whether they are the same, I will soon have an answer...

 

Andrew

[LetItSnow]

With the miles on your machine and a code for the IAC, you may want to clean it. It's an easy enough job... there are some really good instructions on NASIOC. I highly recommend replacing the screws and washers, cos those suckers are S-O-F-T! I did it on my Legacy, and it obliterated the problem I had with occasional idle dips after stopping.

 

You won't believe how much junk is probably in there. Ook.

[adavesAK]

I also got a P1507 on my '98 LGT, but it didn't come up until after it had been put in the shop. O.O

 

I'm curious as to a potential fix (if the shop won't fix it, which they should have done in the first place) for that. However, I don't know about the rest of you, but I have a passenger-side-rear-of-manifolds-mounted IAC, it doesn't rest on top of the throttle body.