01 Don't Panic! Understanding Why Water Is Coming From Your Ca… • 02 2025 Polestar 4: The Electric SUV-Coupe with No Rear Window • 03 11 Reasons Your Car Won't Start and How to Resolve Them • 04 You Could Turn A Cheap Repair Into A Catastrophic Bill By W… • 05 Adapting to Autonomous Transmissions: How Self-Shifting Car… • 06 Types of Spanners: Uses, Advantages, and Material Compositi… • 07 Drivers Just Learned Why Their Car Alarm Randomly Goes Off … • 08 How Long Can a 4 Cylinder Car Last? • 09 Experts Reveal Why That Blue Tinted Strip At The Top Of Win… • 10 5 Things You Should Know About Oxygen Sensors in Cars •

DTC codes / Nissan codes / P1125

P1125 · NissanTandem Throttle Position Sensor Circuit Fault

P1125 on Nissan vehicles indicates that the engine control module (ECM) has detected an electrical fault in the tandem throttle position sensor circuit, which typically involves two sensors that must agree. The ECM compares the signals from both sensor tracks and sets this code when the voltages are out of range, inconsistent with each other, or not responding as expected during throttle movement.

SystemPowertrain
Code typeNissan specific
SeverityMedium
Fix difficultyIntermediate
AreaFuel and air metering

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp) on the dashboard.
  • Often no symptoms besides the warning light, especially if the fault is intermittent.
  • Reduced engine performance or limp mode, limiting power and speed.
  • Poor throttle response or hesitation when accelerating.
  • Rough idle or stalling, particularly when coming to a stop.
  • In some cases, the engine may enter a fail-safe mode with fixed idle speed.

Common causes, most likely first

  1. Faulty tandem throttle position sensor (one or both sensor tracks worn or damaged).
  2. Wiring harness damage such as chafed wires, corrosion, or loose pins in the connector at the throttle body.
  3. Poor electrical connection at the throttle position sensor or ECM connectors.
  4. Contamination or carbon buildup on the throttle plate or sensor contacts affecting signal output.
  5. ECM software issue or internal fault in the throttle control circuit (less common).
  6. Aftermarket or incorrectly installed throttle body causing signal mismatch.

How to diagnose and fix it

  1. Use an OBD-II scanner to retrieve the code and freeze-frame data, then clear the code and test-drive to see if it returns.
  2. Visually inspect the throttle body, sensor connector, and wiring for damage, corrosion, or loose pins; repair as needed.
  3. Backprobe the tandem throttle position sensor connectors and measure reference voltage (typically 5V) and ground integrity with a multimeter.
  4. Monitor both sensor signal voltages with a scan tool while slowly opening the throttle; they should track together and change smoothly without drops or spikes.
  5. If signal voltages are out of specification or inconsistent, replace the throttle body assembly (which includes the tandem sensor).
  6. After replacement, perform a throttle body relearn or idle air volume learning procedure using a scan tool or manual procedure.
  7. Clear codes and verify repair by test-driving under various conditions, ensuring no pending or stored codes return.

Tandem Sensor Mismatch and Wiring Traps

  • A common mistake is replacing the throttle body without first checking the wiring harness for intermittent shorts or opens, which can mimic a failed sensor.
  • The tandem throttle position sensor actually consists of two separate potentiometers; the ECM sets P1125 when their signals deviate beyond a calibrated threshold, so a single dirty track can trigger the code.
  • Carbon buildup on the throttle plate can cause the sensor to report incorrect positions at idle, leading to this code even when the sensor itself is healthy.
  • After any throttle body cleaning or replacement, a relearn procedure is mandatory on many Nissans; skipping it can cause P1125 to reappear immediately.
  • This code can be set by a weak battery or charging system issue that causes voltage spikes, so always verify battery and ground connections before condemning the sensor.

Can I keep driving with P1125?

If the check engine light is on but the vehicle drives normally, you can drive cautiously to a repair shop, but avoid aggressive acceleration or heavy loads. If the engine enters limp mode or runs poorly, limit driving to a short distance to prevent safety risks.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for Nissan vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.

Running on fumes Free guides aren't free to make. Top up the tank. Any amount, one time. Fuel the Garage