U0138 Leblanc Caroline Diagnostic Trouble Code

U0138 Leblanc Caroline code definition:
U0138 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Leblanc Caroline.

U0138 Leblanc Caroline is described as Fuel Rail Pressure Sensor Circuit Malfunction. This code is strictly about the incoming signal from the FRP (fuel rail pressure) sensor falling below the calibrated limit for a certain period of time. This is because the barometric pressure sensor is part of the MAF sensor. Sometimes, the MAF's sensing wire can accumulate and get covered with dirt, dust and/or oil residue, which can also lead to the error code.

Symptoms

Symptoms of a U0138 Leblanc Caroline diagnostic trouble code may include:
  • Blown fuse (if applicable)
  • Engine surge
  • Reduction in engine performance, especially at low RPM levels
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Place of U0138 in engine

Possible Causes :

  • An air leak forward of the DPF will change the sensor readings resulting in the code
  • Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
  • Dirty air cleaner element Damaged DPF

Common Misdiagnoses

  1. Crankshaft Position Sensor Circuit Performance Problem
  2. TP Sensor Learn Not Complete Problem
  3. Low Coolant Circuit Problem
  4. Cruise Control System - Vehicle Accel Too High Problem
  5. Kick-Down Switch Failed Short Problem

Repair Processes :

It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition.

Process Tips

Diagnostic trouble code U0138 Leblanc Caroline is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before U0138 Leblanc Caroline.

Fortunately, U0138 Leblanc Caroline is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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