Help me diagnose my CEL - Subaru WRX Forum
 
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post #1 of 5 Old 08-04-2009, 03:29 PM Thread Starter
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Help me diagnose my CEL

My check engine light has been coming on a lot recently and my Cobb AccessPORT V2 keeps telling me it's these same six codes:

P1518 – Starter Switch Circuit Low Input
P0852 – Neutral Switch Input Circuit High
P1153 – O2 Sensor Circuit Range/Performance (High) (Bank 1 Sensor 1)
P1152 – O2 Sensor Circuit Range/Performance (Low) (Bank 1 Sensor 1)
P0502 – Vehicle Speed Sensor Circuit Low Input
P0503 – Vehicle Speed Sensor Intermittent/Erratic/High

It first happened in February, 2008 the day after I installed my Cobb catted downpipe and flashed my ECU to Cobb's Stage 2, 93 Octane map. I was under the impression that the AP maps were supposed to block any CEL codes related to having a TBE, so I decided to give it a little time and see if maybe my ECU would learn enough to block them. Each time the CEL came on, I used my AP to read the codes and reset the ECU. That February, the CEL came on four times, and every time I checked and cleared them and then they stopped for a while.

I was fine for a year and three months and, starting again in May 2009 up until now, seven more CELs came on with those same six codes. I don't want to start spending money unnecessarily replacing things that might not be broken, so I'm asking for everyone's help to see if: (1) anyone else is experiencing this problem or anything similar, and (2) what are some suggestions to diagnose and/or fix the problem?

I have noticed that since I replaced my spark plugs with Pulstars, the car seems to be idling ever so slightly rough, making an occasional pop or gurgle here and there, but I've read that the boxer engines normally don't idle completely smoothly and the same six codes were popping up in February, 2008 which was way before I installed the plugs, so I don't think that has anything to do with my problem. Most of the time, the CEL comes on shortly after I start the car after it's been parked for a period of hours after work/shopping/etc.

I have a current list of mods in my profile. I always use Shell V-Power 93 Octane gas. I always let the car cool down for a little bit before shutting it off. Is the generic off-the-shelf Cobb map to blame - do I need to get a professional tune to take care of this issue? Is the weather somehow to blame? Is my free-flowing exhaust not creating enough backpressure for my engine? Are the spark plugs to blame - should they be gapped smaller than factory specs? Do I have a bad O2 sensor, speed sensor, starter switch, and neutral switch? I can't figure out why this is happening. Please offer any suggestions you might have because I'm just about out of ideas. ...and I don't want to go back to stock because I love my Stage 2 power It's funny because when the CEL is on and the cruise control light flashes (I presume this is limp mode), the car seems to idle and drive smoother - I don't get it

Help.

John
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post #2 of 5 Old 08-04-2009, 05:38 PM
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CEL on and Cruise light flashing - NASIOC

Read the whole thing but i think post #9 is from someone that actually had the problem and found a proper solution. It's something to do with '07s secondary air pumps valves sticking in the open or close position.

also make sure your green connectors were unplugged after the tune.

rollin on 17's now and they're dirty
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post #3 of 5 Old 08-04-2009, 05:49 PM
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4 CELs...err what... - NASIOC

Found this one as well. It could also lead to a bad ground. Did you disable your DRL?

rollin on 17's now and they're dirty
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post #4 of 5 Old 08-05-2009, 12:04 AM Thread Starter
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Hmm, I guess I'll have to start spending some time over at NASIOC

Yep, I always make sure my green connectors are unplugged when I'm done and nope, my daytime runners have not been disabled. I'll have to go back and double check the wiring for my Hella Supertones and SharpHID low beam kit - and, come to think of it, I completely removed the tiny driving lights from my headlights under where the orange reflectors used to be. Maybe that has something to do with it. A bad ground would certainly seem to make sense.

Thanks so much guys, I'll have to do some investigation when I get a little free time and I'll let you know if I come up with anything.

John
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post #5 of 5 Old 08-05-2009, 12:26 AM
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Good luck with it John.

Joshua
"2007 WRX- PPG'd, 20G- Tim Bailey tuned
Stage 2 2005 WRX
Cobbtuning.com"
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