Subaru Diesel Sluggish Start + Rough Idle Fix Needed

Had similar symptoms on a 2008 Subaru Outback diesel. The sluggish response and poor fuel efficiency pointed to a faulty accelerator pedal module. Initially tried throttle cleaning, but it only provided temporary improvement. The real issue became clear when diagnostic tests showed irregular voltage readings from the pedal position sensor. Engine idle remained unstable even after cleaning the throttle body and control valve. The engine throttle would sometimes fail to respond properly to pedal input, especially during cold starts. The complete repair required: Replacement of accelerator pedal module, Throttle cleaning service, Control valve recalibration, ECU reset This was a serious repair that required specialized diagnostic equipment. The fault gradually developed over time, making it easy to miss during routine inspections. After replacement, the engine response returned to normal, idle smoothed out, and fuel consumption decreased significantly. Recommend getting a second opinion from a workshop with Subaru-specific diagnostic tools, as generic scanners might miss the pedal module fault codes.

Thanks for sharing your experience. Your solution definitely sounds similar to what I am going through. The rough engine idle and poor fuel efficiency match my symptoms exactly. The car throttle response is getting worse by the day too. My current mechanic seems hesitant about checking the pedal module. Did you notice any warning lights before getting it diagnosed? Also, would be helpful to know roughly how much the complete repair cost and if youve had any recurring issues since the fix?

After getting the accelerator pedal module replaced and proper throttle cleaning done, my Subaru Outback has performed flawlessly. The engine throttle response improved dramatically and fuel efficiency returned to normal levels. The total repair cost came to 205€ for the pedal module replacement. Interestingly, no warning lights appeared on the dashboard before the diagnosis. The symptoms just gradually worsened, particularly the rough idle and inconsistent throttle position response. The specialized diagnostic equipment was crucial in identifying the exact issue. Its been over a year since the fix, and I havent experienced any recurring problems. The engine runs smoothly, starts perfectly, and maintains steady idle. If your mechanic seems unsure, definitely seek out a specialist who has experience with throttle valve systems in Subarus. The investment in proper diagnosis and repair is worth it for the improved performance and fuel economy.

Finally got the car checked at a different mechanic who specializes in Subarus. The air intake system was completely clogged and the throttle position sensor was failing intermittently. They performed a thorough throttle body cleaning and replaced the faulty sensor. The total repair came to 180€ but the difference is remarkable. The engine idle is steady now and the sluggish response is gone. Fuel efficiency has improved significantly, getting about 15% better mileage than before. What really impressed me was how the specialist mechanic immediately identified the issue using their diagnostic equipment. They showed me the before and after readings of the throttle position sensor, which explained the inconsistent performance I was experiencing. Definitely learned my lesson about getting a second opinion when the first repair attempt doesnt solve the problem. The car runs like new now, and I finally feel confident about its performance again.