What Does B2105 Mean?
B2105 indicates the Body Control Module (BCM) or Engine Control Module (ECM) has detected a throttle position sensor signal that is below the acceptable voltage threshold or operational range. This code specifically relates to the throttle position input circuit reporting an abnormally low voltage, suggesting the sensor cannot properly communicate throttle angle to the control modules. This affects the vehicle's ability to monitor and control engine power output and may trigger limp mode or reduced performance.
Common Causes
35%
Faulty throttle position sensor (TPS) with internal circuit failure or worn potentiometer tracks
30%
Damaged or corroded wiring/connectors in the TPS signal circuit, particularly between sensor and BCM/ECM
20%
Poor ground connection at TPS sensor or control module causing voltage drop in reference circuit
10%
Shorted signal wire to ground or damaged BCM/ECM input circuit
5%
Contaminated or mechanically stuck throttle body preventing proper TPS operation
Diagnostic Steps
1
Step 1: Perform visual inspection of TPS connector and wiring harness for corrosion, bent pins, water intrusion, chafing, or damaged insulation. Check connector security and ensure proper seating.
2
Step 2: Using a digital multimeter, backprobe the TPS signal wire at the sensor connector with ignition ON/engine OFF. Verify reference voltage (typically 4.5-5.0V) and signal voltage (should be 0.5-1.0V at closed throttle). Compare readings to manufacturer specifications.
3
Step 3: Check ground circuit continuity by measuring resistance between TPS ground pin and battery negative terminal (should be less than 1 ohm). Also verify signal wire continuity from TPS to BCM/ECM connector.
4
Step 4: Monitor TPS voltage live data while slowly opening throttle from closed to wide-open position. Signal should sweep smoothly from approximately 0.5V to 4.5V without dropouts, spikes, or flat spots indicating sensor failure.
5
Step 5: If wiring and voltage tests are normal, substitute a known-good TPS or throttle body assembly to confirm sensor failure. Clear codes and perform relearn procedure per manufacturer specifications.
6
Step 6: After repair, verify TPS voltage sweep is smooth across entire range, clear all codes, perform drive cycle, and confirm no code recurrence with proper throttle response.
Estimated Repair Cost
$75 - $450
Parts + labor, varies by vehicle and location
B2105 indicates the Body Control Module (BCM) or Engine Control Module (ECM) has detected a throttle position sensor signal that is below the acceptable voltage threshold or operational range. This code specifically relates to the throttle position input circuit reporting an abnormally low voltage, ...
The most common cause of B2105 (Throttle Position Input Out of Range Low) is: Faulty throttle position sensor (TPS) with internal circuit failure or worn potentiometer tracks
Typical repair costs for B2105 range from $75 to $450, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Vehicle may enter reduced power/limp mode limiting acceleration and top speed, making it unsafe for highway driving or emergency maneuvers. While the vehicle may remain drivable at low speeds, repair should be completed promptly to restore full throttle control and prevent potential stalling.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to B2105 to identify the root cause.
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Quick Info
Category
Body
System
Throttle Control System / Body Control
Difficulty
Type
Generic (SAE)
Recommended Tools
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