The Subaru CEL thread

[Justthetom]

Background Info:
2000 Impreza OBS(manual), two owners(including me), well maintained and (almost always) serviced on time. 267k miles and everything is stock/original to the car minus the scheduled replacement parts and a swapped throttle body from a 1999 Impreza 2.2l (down pipe sprung a leak causing overheating and the "new" throttle body only cost around $70). Not much of a car guy, but I'm learning.

Situation:
I was late on my oil change this time (life happens) and I had just replaced my knock sensor for the code I was throwing originally. My inspection is this month and on my way to the state facility, my check engine light comes on. I go to auto-zone to get them to read the code for me and they tell me "The code is p0420 which is your catalytic converter. It's showing up twice.". Knowing very little about cars, I take to the internet for research.
After about a half an hour of reading, I feel like my worst nightmare has been realized and I have to replace the whole cat and possibly my whole exhaust. But then I take to the forums here and find a whole slew of information.

Solution (so far):
I waited until my gas tank was close to empty, put in catalytic converter cleaner (Redline) and drove (agressively on the highway/slow and steady around town) until I had to refuel. Filled up the tank and then dumped in a whole can of seafoam. I did some more highway driving (including 3 distinct pulls from 30mph to 80mph) and then around town driving like a "sensible grandpa". I returned home for several hours and, from a cold start, drove down a road that had intermittent stop lights every 4 or 5 miles with an average speed limit of 45-50mph for about an hour. When I woke up this morning and went to start Lucy Sue the Subaru to warm her up, no more codes. Checked in with auto-zone as well and they confirmed no codes.

I'm not sure if this is going to last longer than a day or two or if I'm actually in the clear, but I do hope this was helpful to someone.

P.S. definitely replacing the entire exhaust soon. Exhaust front to back is all original and truth be told, that kind of scares me haha.

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[Travistee]

I hit a rock that I couldn't see while backing up.
It broke the tail pipe off of the muffler.
The muffler shop cut the pipes, put on a sleeve and welded it.
That was on Monday. On Friday I got a check engine light. I don't know exactly how many miles I drove after it was welded. Maybe 50 . I drove about 20 miles before I got it welded. I supported the tail pipe by hanging it with a wire.

The shop also told me there could be some leakage where the CAT connects to the the tailpipe. I didn't ask them to do anything for that since I didn't know if it was going to be a problem or not. They didn't notice any other problems.

My code reader says P0420 Catalyst system below threshold Bank 1.
Could the code have been caused during the time the pipe was not connected to the muffler?
I cleared the codes today to see how long or if it comes back.

I haven't had any other codes for about two or three years.
Could a leak at the CAT - tailpipe cause that.

I want to get some opinions here before I go back for them to look at it again.
Edit:. 60 miles after I cleared the codes no check engine light.
I have the original exhaust system including the O2 sensors . No need to replace anything.

Mileage 197K

Thanks

[CarolineK]

I have a 2007 WRX, stock, with 94K and the CEL has been on for 2 years. For the past 2 rounds of inspections I've got it cleared long enough to get a sticker and it pops back on within hours of getting the sticker.

This year it will no longer clear (P0410 Secondary Injection System) and I dumped $1.5K to replace the secondary injection system (locked solenoids). The light came back on after the work with a few new codes and still won't clear with multiple resets. Earlier this year I had a fuel leak (corroded lines). And just this week the transmission has started slipping (no acceleration in 3rd and 4th). At this mileage, the clutch isn't a surprise, it is original.

What is happening here? Its pouring and my mechanic suggested I start thinking about a replacement. What is the experience on common issues with this age of a WRX? Things seem to be corroding and I am 2 months overdue on a sticker.

[Alittlewhitewagon]

I have a 2012 WRX with: Stage 2 accessport, turboback exhaust, cobb recirculating valve, Grimspeed air oil seperator, cobb light weight pully, cobb intake, cobb turbo inlet, and cobb boost control solenoid. (i have suspension mods as well but irrelevant)

I overboost if i make a pull in 4th or 5th gear WOT, Ive gotten to 21 PSI, at which point I get a CEL for overboosting. I am not sure why the car is doing this.

[ForeverAfflicted]

i have a 2008 WRX pretty much stock except what i believe to be an CAT back exhaust. It originally had a blow-off valve which i have removed due to the excessive air leak it was causing, and after that it threw codes for system too lean and misfire in 1,3,4 about 100km later. ive had it smoke tested and could find no further vacuum leaks, compression and leak down tested it last weekend and i believe the results to be good. since putting it back together after the tests there is no more lean code and it seems to consistently be codes for misfire in 1 and 4 but 3 would occasional pop up after a battery reset but go away later. looking for advice on what might be the cause, going to swap coils and replace spark plugs but plugs were replaced less the 15k ago, could bad gas or injectors cause this? i have a scan tool and getting very rich numbers from the o2 sensor and very positive short and long term fuel trims both at idle and 2500rpm.

any advice would be much appreciated

thanks

[CaptainSlowbaru]

Originally Posted by ForeverAfflicted

i have a 2008 WRX pretty much stock except what i believe to be an CAT back exhaust. It originally had a blow-off valve which i have removed due to the excessive air leak it was causing, and after that it threw codes for system too lean and misfire in 1,3,4 about 100km later. ive had it smoke tested and could find no further vacuum leaks, compression and leak down tested it last weekend and i believe the results to be good. since putting it back together after the tests there is no more lean code and it seems to consistently be codes for misfire in 1 and 4 but 3 would occasional pop up after a battery reset but go away later. looking for advice on what might be the cause, going to swap coils and replace spark plugs but plugs were replaced less the 15k ago, could bad gas or injectors cause this? i have a scan tool and getting very rich numbers from the o2 sensor and very positive short and long term fuel trims both at idle and 2500rpm.

any advice would be much appreciated

thanks

Check the MAF... I bet it's filthy dirty. What is the a/f sensor reading? It should sit right at 1.00- maybe float from 0.99 to 1.01. If it's reading goofy numbers, it could be a bad a/f sensor, too. Keep us posted!

[SettleForSatin]

Vehicle: 2009 Subaru Impreza OBS (5 speed)
Mileage: 153,000

Problems: Car wouldn't start when half warm. Started up from cold (even at 10 degrees F), and started up from hot, but not in between. Would crank but not start until after at least a few attempts, and would be greeted with a CEL.
CEL code definition: Crankshaft Position Sensor

Fix: Replacing the old sensor with a new one. The thing was corroded in there pretty good. It was a pain to replace, but a few weeks later and the car is still working alright.

[Darynk99]

Code came on my 03 WRX, catless exhaust, 170k miles, etc. where do I even start with this code (P0447)

[Jamiejo830]

My car is throwing codes like it's in test mode, but I don't believe a 2008 has the green wires.
Any ideas for p0851 neutral safety, low voltage?
Have several bolt ons. FMIC, BOV, Headers, intake, exhaust. Currently just on Cobb stage 2+. Will protune once I clear up CEL and issues. Also, has 02 sensor codes.

Thanks for any help.

[Thrillz]

2008 Impreza 2.5 sedan
Stock exhaust and engine


Hey guys, sorry if this has been addressed already, but I didn't see anything directly relating to my problem and I am short on time.

My car died yesterday while driving in the middle of the interstate. I didn't hear any loud noises but the road noise was high. The car just shut off going up a bridge and I coasted to the bottom of the other side. When I turn the key it sounds like the starter is working but the engine isn't turning over. I thought maybe it had something to do with the timing belt but I haven't been able to look yet. I replaced it around 100K and the car currently has about 168K.

As far as the P0420 a few months ago the car was running rough and loud and I took it to a shop. The flanges just before the mufflers were rotted and they replaced them with some welded sections. Seemed to run fine after that up until now. The code started a little more than a week ago and I figure my catalytic converter is shot but it was driving alright.

Yesterday morning the P0420 code was still on when I drove to work (about 51 miles). When I parked the car it smelled hot. I checked the oil and it was low. I just did an oil change about a month ago, so something is leaking. I put more oil it in and got it where it's supposed to be. I was going to check it again when I got home but I didn't make it.

So my question is... are these things related? Where should I start? If I take it to a shop then it needs to be towed and I need to make sure they can do everything at once. If I try to diagnose it at home then I'm going to have to get a rental car. It's kind of hard to assume which will be cheaper. Some people tell me bolt on exhaust systems are something I could do myself in my garage, but I've never done anything on exhaust systems before. Any advice would be appreciated. Thanks!

[Shadowz Edge]

P1449 x3: EVAP Code definition unknown to me.
2012 Impreza Hatchback FB20/CVT
31,000 miles (I'm the original owner)
Haven't fixed yet.

Driving along yesterday my CEL, TCL, and Flashing Cruise all started at the same time. Finally got the codes pulled on my scanner and found P1449 was in there 3 times. I had just filled up the day before so I checked the fuel cap but with a little research on here I ran across a possibility of a spider web blocking a vent of some kind. I have currently cleared 2 of the 3 codes as the 3rd one will not delete and my scanner says it's a permanent code. Where can I look to see if a spider has indeed built a web blocking that vent causing the code to set?

Thanks in advance everyone!

[Reddogg33]

P0500 Vehicle speed sensor malfunction

2009 Subaru Sti hatchback

245000 km

Car threw this code randomly upon startup. I cleared the code and it was fine for a few days, but now it comes back everytime I start the car after clearing. The weird thing is that the car seems fine and the speedometer even still works. So my other problem is trying to figure out if my car has a vehicle speed sensor on the transmission or does it use the abs sensors as the speed sensor? I've searched online and keep finding conflicting info about this. And if my car uses the abs sensors how do I figure out which one is causing the issue?

[lxrubin]

I have a 2008 Impreza 2.5L NA, ~220,00mi, 5 spd manual.

Yesterday it got a CEL for P0026 & P0028 (Intake Valve Control Solenoid Circuit Range / Performance Bank 1 & 2). I cleared the codes and haven't gotten the CEL back. Other than the light, I didn't notice anything wrong.
Additionally, the oil pressure light came yesterday, It was down a couple quarts. I had never checked it since I bought it, so not sure if it's a new issue...

Today it was cold, about 40°F, but not the coldest it's been lately. It was very difficult to start. I cranked for over 5 seconds. I tried to back out in reverse and stalled. I've never stalled the car before. It restarted fine and I pulled out by feathering the clutch. I didn't stall again, but I needed to slip the clutch more than usual. Driving to work, whenever I came to a stop and took it out of gear, the engine would drop below 500rpm and studder back to normal idle speed. When up to speed, I didn't notice a loss in power.

Does anyone know what might cause this? Are the CEL codes and the starting, low rpm issues related?

[lxrubin]

I think I resolved the issue, so I may as well post here. After doing a lot of research, I found that old dirty oil, or insufficient oil will affect the VVT system, throw those codes, and affect performance. I changed the oil and it appears that the performance has returned and there was no issue starting or idling today. While under there, it appears that the valve covers are leaking, or at least something from the area, and I'll investigate it further in the coming months. Until then, I'll monitor the oil level.

[Jml3837]

I bought the new-to-me sti a week ago. Earlier in the week I got a p0340, camshaft position sensor. I got the CEL after a hit a pothole. The car didn’t drive or sound any different. Erased the code and it didn’t come back.

Today, just driving down a road in stop and go traffic, p0300 and p0302, cylinder 2 misfire. No change in performance or sound.

Taking it to the dealer on Monday. I hope this isn’t a sign of things to come.

[Bishop]

Originally Posted by Shadowz Edge

P1449 x3: EVAP Code definition unknown to me.
2012 Impreza Hatchback FB20/CVT
31,000 miles (I'm the original owner)
Haven't fixed yet.

Driving along yesterday my CEL, TCL, and Flashing Cruise all started at the same time. Finally got the codes pulled on my scanner and found P1449 was in there 3 times. I had just filled up the day before so I checked the fuel cap but with a little research on here I ran across a possibility of a spider web blocking a vent of some kind. I have currently cleared 2 of the 3 codes as the 3rd one will not delete and my scanner says it's a permanent code. Where can I look to see if a spider has indeed built a web blocking that vent causing the code to set?

Thanks in advance everyone!

Did you get this code figure out?