Nissan/Infiniti B2105: TPS Voltage Too Low
Diagnostic trouble code B2105 indicates that the throttle position sensor (TPS) signal voltage is below the minimum expected range, typically near 0V or less than 0.1V. This code is specific to Nissan and Infiniti vehicles and suggests an open circuit, short to ground, or internal sensor failure. The TPS monitors throttle plate angle and is critical for air-fuel mixture calculations and transmission shift strategy.
1. Commonly Affected Makes
2. Most Common Causes
- Faulty or worn throttle position sensor
- TPS signal wire shorted to ground
- Open circuit in the TPS signal wire
- Corroded, loose, or damaged TPS connector
- Failed 5V reference voltage from the control module
- Intermittent wiring harness issue near the throttle body
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Poor acceleration or hesitation
- Rough idle or stalling
- Transmission shifting issues
- Reduced fuel economy
4. Step-by-Step Diagnosis
Scan for codes and verify B2105 is present
Inspect TPS connector for corrosion, damage, or loose pins
Measure TPS signal voltage at idle (should be ~0.5V) and wide open throttle (~4.5V)
Check for 5V reference voltage at the TPS connector
Test continuity of TPS signal wire and ground circuit
If all wiring checks out, replace the TPS sensor
5. Frequently Asked Questions
Is it safe to drive?▼
You can drive short distances, but the vehicle may experience poor performance, stalling, or transmission issues. It's best to diagnose and repair promptly to avoid further damage.
How much does it cost to fix?▼
Typical repair cost ranges from $150 to $400, including parts (TPS sensor $50-$150) and labor (1-2 hours at $100-$150/hour).