P1124
NissanThe Powertrain Control Module (PCM) or Engine Control Module (ECM) has detected that the signal from the Throttle Position Sensor (TPS) is outside of its predetermined self-test operating parameters during a specific diagnostic routine. This indicates an illogical voltage output range.
Medium SeverityThis code signifies that the Engine Control Module (ECM) has identified an abnormal voltage reading from the Throttle Position Sensor. Essentially, the ECM isn't seeing the expected electrical signal for the throttle plate's position, which can disrupt precise fuel and air metering.
⚠️ Before You Begin (Safety First)
Always ensure the vehicle is secured on a level surface with the parking brake engaged before commencing any diagnostic or repair procedures. Disconnect the battery's negative terminal when working with electrical components to prevent accidental short circuits or system damage. Operating a vehicle with an erratic throttle position signal could lead to unpredictable engine response, potentially compromising vehicle control.
Common Symptoms
- Illogical or erratic engine RPM at idle
- Noticeable hesitation or surge during acceleration
- Activation of a "limp mode" where engine power is reduced
- Inconsistent throttle response
- Check Engine Light illumination
Common Causes
- Degradation or failure of the Throttle Position Sensor (TPS) itself
- Corrosion or damage within the TPS electrical connector
- Fraying, shorting, or open circuits in the TPS wiring harness
- Interference or resistance in the low-reference or 5V reference circuits to the TPS
- Rarely, an internal ECM processing fault regarding the TPS input
Frequently reported on: 2002-2006 Nissan Altima 2.5L, 2000-2006 Nissan Sentra 1.8L, 2005-2007 Nissan Pathfinder 4.0L, 2004-2006 Nissan Maxima 3.5L
Diagnostic Steps
- Connect an OBD-II scan tool to confirm the P1124 code and check for any additional related codes.
- Visually inspect the Throttle Position Sensor and its wiring harness for obvious signs of damage, fraying, or loose connections.
- With the ignition on (engine off), monitor the TPS voltage output using a multimeter or scan tool while manually actuating the throttle plate from closed to wide open. Observe for smooth, linear voltage changes without drops or spikes.
- Verify the 5-volt reference and ground circuits at the TPS connector are stable and within specifications.
- If the sensor exhibits erratic readings or incorrect voltage ranges, proceed with replacement of the Throttle Position Sensor.
- Clear the DTCs and perform a throttle relearn procedure if applicable for your specific Nissan model.
- Road test the vehicle to confirm proper operation and ensure the code does not return.
👨🔧 When to Call a Professional
If initial diagnostics involving wiring inspection and basic sensor replacement do not resolve the issue, or if the problem persists after clearing the code, it's prudent to engage a professional. Advanced diagnostics may be required to verify ECM integrity, analyze signal integrity under load, or address potential underlying network communication issues that could be affecting the TPS signal interpretation.
Commonly Asked Questions
How does the ECM determine the TPS is 'out of self-test range'?
The ECM performs internal diagnostic routines. During these checks, it expects to see the Throttle Position Sensor's output voltage within a predefined minimum and maximum threshold. If the signal falls below the minimum or exceeds the maximum expected voltage during these specific tests, the ECM registers it as 'out of self-test range' and sets P1124.
Can a dirty throttle body cause this code?
While a dirty throttle body primarily affects airflow dynamics and idle quality, it can indirectly influence the mechanical movement of the throttle plate. If carbon buildup prevents the plate from returning to its true closed position, the TPS might report an open-throttle voltage that the ECM considers out of range for an idle condition, thus triggering the code.
Is recalibration or relearning necessary after replacing the TPS?
For many Nissan applications, especially those with drive-by-wire systems, a throttle body or TPS relearn procedure is often critical after component replacement or battery disconnection. This procedure allows the ECM to 'learn' the new sensor's precise minimum and maximum voltage values corresponding to the throttle plate's physical stop positions, ensuring accurate airflow modeling.
What happens if I ignore the P1124 code?
Ignoring P1124 can lead to progressive drivability issues. The ECM relies on accurate TPS data for fuel delivery, ignition timing, and transmission shift strategies. A compromised signal will result in inaccurate air-fuel mixture control, potentially causing poor fuel economy, reduced engine power, rough idling, and in some cases, activate a 'failsafe' or 'limp mode' to prevent engine damage.