2005 Subaru Legacy cruise control problems
severe 11 complaints filed with NHTSA · avg repair $600 · see cruise control across all vehicles →
Among the 11 model years of Subaru Legacy in our records for cruise control problems, this one ranks #2 by owner-complaint volume.
The failure pattern owners describe
Owners of 2005 Subaru Legacy models report five distinct throttle and cruise control problems. The most common is cruise control randomly disengaging while driving, causing sudden loss of speed on highways and under normal conditions. When this happens, the cruise light stays on but the set light goes off and engine loses acceleration; resetting doesn't fix it.
Separately, the throttle becomes unresponsive—the accelerator pedal produces no engine response, causing the vehicle to idle uncontrollably. Check engine code P2138 (Throttle Position Sensor) appears in these failures. One owner says this has happened over 20 times. Another found the issue recurred after the car was turned off and back on several times before throttle response returned. One owner reports a previous owner experienced the same problem.
Two owners report sudden unexpected acceleration: one at 65 mph had to shift to neutral and kill the engine to regain control; another couldn't brake to stop the vehicle in a parking lot. A fourth complaint describes throttle surging under light load, especially on highway downhill grades with cruise control on—the dealer said this is normal.
A fifth owner simply states sudden loss of acceleration power at various speeds. Owners have not located recalls or TSBs addressing these issues, though some found online discussions of similar problems in other 2005 Legacy owners.
Same Subaru Legacy cruise control reports on nearby years: 2006
Failure modes owners describe
Cruise Control Intermittent Disengagement
Cruise control randomly disengages or fails to maintain speed under normal operating conditions. Owners report the cruise light stays on while the set light turns off and engine loses acceleration. Attempting to resume or reset cruise does not resolve the issue. Occurs across a wide range of speeds (50-70 mph), weather conditions, and road grades.
When: 22,500 mi to 190,000 mi; no single operating condition identified
Symptoms owners cite: Cruise control light stays on, set light turns off; Engine loses acceleration when cruise fails; Resuming/resetting cruise does not fix problem; Sudden and unexpected loss of vehicle speed; Occurs intermittently on highways and under normal driving
Throttle Position Sensor Failure / Unresponsive Throttle
Engine loses throttle response, with the throttle becoming unresponsive despite accelerator pedal input. Check engine light illuminates with code P2138 (Throttle Position Sensor Voltage Correlation). One owner reports the issue was solved by changing the throttle control to an updated version using Hall Effect method instead of rheostat. One owner reports this has occurred more than 20 times.
When: 110,000 mi to 146,000 mi; at least one occurrence at 60 mph on highway
Symptoms owners cite: Throttle unresponsive when pressing accelerator; Engine revs high but car will not move; Engine goes to idle, throttle becomes unresponsive; Pressing accelerator produces no response; Check engine light illuminates
Codes mentioned: P2138
Repairs/costs cited: One owner reports changing throttle control to updated Hall Effect version resolved the issue
Unexpected Vehicle Acceleration
Vehicle independently accelerates at rapid speed without driver input. In one report, owner was unable to stop the vehicle with brakes while in a parking lot. In another, owner traveling at 65 mph experienced sudden acceleration and had to shift into neutral and shut off the vehicle to resume normal operation. Problem recurred on numerous occasions in that instance.
When: 65 mph cruising; parking lot; recurred on numerous occasions
Symptoms owners cite: Vehicle independently accelerates at rapid speed; Unable to stop vehicle with brakes; Sudden acceleration during normal driving; Recurs on multiple occasions
Throttle Surge Under Light Load with Cruise Control
Manifests as surging throttle response under very light load conditions, most noticeable on highway downhill grades with cruise control enabled. Also occurs when manually controlling throttle—minimum throttle input produces too much acceleration, while less input causes engine to drop to idle. Dealer stated this is normal operation. A separate cruise control failure issue was repaired with no effect on the surge problem.
When: Continuous issue; occurs on highway downgrades
Symptoms owners cite: Throttle surge under very light load with cruise on; Difficult to maintain desired speed manually on downgrades; Minimum throttle input too much; less causes idle drop; Most noticeable on highway grades
Repairs/costs cited: Dealer stated normal operation
Loss of Acceleration Power
Engine suddenly loses acceleration power while traveling at various speeds. Vehicle will not accelerate despite engine operation. No check engine light or diagnostic information provided in this complaint.
When: 110,000 mi; at various speeds
Symptoms owners cite: Sudden loss of acceleration power; Vehicle does not accelerate at various speeds
Synthesized from 11 NHTSA owner complaints — unverified consumer allegations, summarized for patterns. The verbatim filings appear below.
What owners are reporting 0 most recent
Common questions
How serious is the cruise control problem on the 2005 Subaru Legacy?
It's a meaningful issue. 11 complaints have been filed and the failure mode causes operational problems for owners. Repairs average $600.
At what mileage does the cruise control typically fail?
Across the 8 complaints that reported odometer mileage, most cruise control failures cluster between 66,000 and 190,000 miles, with the median around 141,000. A quarter of owners report trouble before 66,000; a quarter make it past 190,000. Maintenance history matters more than the odometer alone — this is the reported failure window, not a guarantee.
What does it cost to fix?
Independent shops typically charge around $600 for cruise control repairs on this vehicle. Dealer pricing tends to run 20-40% higher. The exact figure depends on the specific failure mode, parts availability, and your local labor rates. If you're outside factory warranty, an extended service contract often covers this category.
Are there any recalls related to cruise control?
No active recalls currently cover cruise control issues on this vehicle. The complaints filed represent owner-reported failures that haven't risen to the level of a manufacturer-issued recall — but they're still worth knowing about before you buy or budget for repairs.