P1140 Load sensing

 P1140 Load sensing

A "P1140 Load Sensing" diagnostic trouble code (DTC) 

indicates an implausible signal from the engine's load sensing system. The exact meaning and cause can differ significantly depending on the vehicle's make and model. 

The load-sensing system uses several sensors to measure the amount of work the engine is doing to help the powertrain control module (PCM) adjust the air-fuel mixture, ignition timing, and other functions for optimal performance. When the PCM detects an inconsistent or unexpected signal from these sensors, it can trigger the P1140 code. 

Vehicle-specific meanings

• Porsche: For some models, such as the Boxster, P1140 points specifically to an implausible load-sensing signal. Possible causes include issues with the cruise control operating cable, a faulty throttle position sensor (TPS), or vacuum/air leaks.
• Nissan: For vehicles like the Pathfinder, P1140 can relate to the variable valve timing control (VTC) position sensor circuit. It can be triggered by a faulty sensor, dirty or low oil, or faulty wiring.
• BMW: On some BMW models, the P1140 code may point to a mass or volume air flow circuit range/performance problem, sometimes caused by oil on the mass air flow (MAF) sensor from an aftermarket air filter.
• Volvo: The code can indicate an oxygen sensor circuit malfunction caused by a faulty sensor or damaged wiring.
• Ford: Some Ford models with a diesel engine can trigger a P1140 code for "Water in Fuel," which illuminates the "Water in Fuel" dashboard light. 

Common symptoms

• Illuminated check engine light (CEL): This is the most common symptom.
• Performance issues: You may notice poor idle quality, rough running, or a loss of power.
• Poor engine response: The engine may surge or hesitate during acceleration.
• Failure to start: In some cases, a severe issue related to this code can cause a no-start condition. 

Diagnostic and repair steps

1. Check for other codes: Since the P1140 code can be triggered by a variety of issues, it's essential to check for other stored codes. These can provide a more specific direction for your diagnosis.
2. Inspect related sensors and wiring: Visually inspect the wiring and connectors for the MAF sensor, throttle position sensor, oxygen sensors, and any other load-sensing-related components for any signs of damage or corrosion.
3. Inspect for vacuum leaks: A vacuum leak can cause false load readings. Listen for hissing noises from hoses and gaskets while the engine is running.
4. Check vehicle-specific components: Depending on your vehicle's make, you may need to check the following:
   • Throttle linkage adjustment on some older Porsche models.
   • Variable valve timing control (VTC) sensors on Nissan models.
   • Fuel system components for signs of a weak fuel pump or "water in fuel" condition.
5. Seek professional assistance: Because of the wide range of potential issues, it's best to consult your vehicle's service manual or a certified mechanic for a proper diagnosis and repair.