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The Scenario:

This weekend I took on a car stereo install. I removed the interior (seats, console and carpet) so I could install dynamat sound proofing on the floor, route some 4 gauge wire to power my amp directly off the battery, and to route a video feed to my newly install backup camera. I did not modify or tamper with the factory wiring harness.

I worked on the car 2 days and each day I had to start the car and pull it out of the garage bay so others could use the lift. It's a car club I belong to and the rule is you can't tie up a bay for days. The car ran fine with no engine light issues.

On the third day I reinstalled the carpet, seats and console and started the car to drive it home. That's when I got a FLASHING CHECK ENGINE LIGHT and the following engine codes:

P0137 = downstream O2 sensor shorted low
P1152 - Front O2 sensor circuit range/performance low
P1153 - HO2S Insufficient Switching bank 2 sensor 1
P0502 Vehicle Speed Sensors Low Input
P0503 Vehicle Speed Sensor Intermittent/Erratic/High
P0851 Park/Neutral Switch Input Circuit Low
P1518 -Starter switch circuit low input

The car runs fine though but the Check Engine light is flashing the entire time I drive. When the engine is off and the key is in the on position, the AC clutch and fans kick on and off even tho AC is switched off.

I rechecked all the wiring harness plugs I had to disconnect for the job and they seem fine.

The car is a 2005 WRX wagon.

I can't help but think something simple is causing this issue and I'd hate to take it to a shop and get charges hundreds of dollar to diagnose the issue.

I did a google search and found that someone else reported a similar issue on a Subaru Help site (unable to post link) but unfortunately no solution was reported.

Any help would be greatly appreciated !!!
 

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electrical can be a huge pain in the ass. you have to start trouble shooting. grab yer volt meter and start chasing wires. check for continuity as well as voltage.

you probably did something by accident and you didnt notice. cut something, cross wires, cut a ground, not enough grounds, too much power drain...

aside the amp, where did you draw power for all the other devices? did u add a new dedicated power and fuse? or did u splice into something. you could be drawing power from other circuits so they arent functioning properly.

"irradic" "shorted" "performance low" "low input".... these all suggest that its getting intermittent power. not enough power or bad grounds can be the culprit of something like that.
 

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Try to reset your ECU and uplug your amps. You just gotta disconnect the Ignition Power source to them, not the big power cables (btw where are you getting that from?)

Like titter said, it's very possible your amps are hitting hard and pulling enough power to compromise the ECU. Are your headlights dimming when the bass hits?

If the above fixes it (disabling power to amps and resetting ECU) one possible solution would be to install those big capacitors as a "surge" power source. They charge up between bass hits and provide power when the bass hits so you're not compromising the power to the computer and you will also have cleaner and more powerful bass.

Another possible option is a bigger battery and a stronger alternator but I do not know if a stronger alternator is available for our cars.
 

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Blinking check engines lights and traction control lights are usually a symptom on limp home mode. that can be caused by a knock event or by the ECU detecting a condition outside the norm. It typically limits boost and tries to keep itself safe.

To reset that you can disconnect the battery and stand on the brake pedal for 10 seconds. It will draing all the power form the system and reset the ECU. Thats not really a solution but it will get you back up and running.

As for solving the issues it almost sounds like you have a dirty ground somewhere. If you have the extra line I would dissconnect your grounds on your amp setup and run them back to the battery directly. Reset the ECU with the process above and try it again. That will eliminate the possibility of a dirty ground signal.
 

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What did you have to unplug besides the radio and the battery?

This sounds like a ground came undone or one of the harness didn't get fully seated back. But hard telling not knowing what you touched.

Can you provide a step by step an maybe some pics hear an there of what you were doing? Sometimes when I go to take a full write up of what I did to post hear I end up finding the problem.
 

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For anyone who stumbles upon this later, it's cause you plugged in something you weren't supposed to. On my 2006 Tribeca it was this little green plug above the PCM.

Not supposed to be plugged in.
46282
 
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