2006 outback , code 2138 throttle position sensor

[montana tom]

2006 outback driving down road at 70 mph , check engine light comes on ... car looses all throttle response (goes to idle) coast to side of road. Engine idles just fine  but will not accelerate. A few times of starting and stopping engine and it suddenly starts working... proceeds to drive 50 miles home without a care. Next day it starts fine and drives 25 miles more to my shop. Code 2138 shows on the computer, throttle position sensor.  Testing showed all working correctly (of course, it drove there) A little checking around on line and i find multiple posts of this complaint. One site recommended reporting it to a safety group in the hope that subaru would own up and fix what could be a life threatening situation. Imagine running 80 mph in the middle of a six lane road and suddenly you lose all throttle... Repair suggestions are vague at best , some think its the connector at the TB servo others swear its the accelerator pedal assembly or connector. Nobody seemed to have a certain fix. Most seemed to change the accelerator assembly and did not report back if that is a permanent fix. Customer wants this fixed, we are way to far out in the boonies to have her car just die with young children with her...  She is willing to buy new sensors at several hundred dollars but I'm not willing to gamble,  that is the fix... only to have her call from the side of the road if its not!  Anybody here had a similar problem?  

[1 Lucky Texan]

is that 06 drive-by-wire? early DBW had a pedal assembly that suffered from issues (moisture?)

 

you might search if DBW - easy swap I think but I haven't done it.

[Fairtax4me]

P2138 looks like a code for the accelerator pedal position (APP) sensor.

First thing I would do is check the commanded values and actual values of the APP sensor in the scanner data. There should be two sensors and IIRC the voltages should be inverse. Compare the no-throttle position voltage to the wide- open position for each.

 

If the values look ok or are more than about .5v apart I would check the connector on the pedal sensor for any dirt or corrosion. Put some di-electric grease in there if it's dry. If the signals are too far apart the ECU sets the code for this sensor. An intermittent problem will be the hardest to replicate, so you probably won't know if it actually needs a new pedal assembly or not until it either happens again or there is something obviously wrong with the wiring or connector.

 

Also check the charging system and battery connections. Make sure both cable terminals are clean and tight. Make sure the main lead to the alternator is tight and clean. Make sure the pins in the small plug on the alternator are clean. Put some di-electric grease there if they're dry.