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