C0129 Fiat 25 Diagnostic Trouble Code

C0129 Fiat 25 code definition:
C0129 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code for Fiat 25.

C0129 Fiat 25 is defined as Ignition Coil B Primary/Secondary Circuit Malfunction.This code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II tool, or vehicles made since 1996 up to present. 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 C0129 Fiat 25 diagnostic trouble code may include:
  • Cherry red hot catalytic converter
  • Poor acceleration
  • The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
  • Reduction in engine performance, especially at low RPM levels
Place of C0129 in engine

Possible Causes :

  • A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
  • Some aftermarket accessories and performance modifications
  • An air leak forward of the DPF will change the sensor readings resulting in the code

Common Misdiagnoses

  1. Vehicle Speed Output Circuit Problem
  2. Cruise Control Servo Indicates Low Problem
  3. A/C System High Pressure High Temperature Problem
  4. PCM Stack Overrun Problem
  5. Transmission Control Module Reprogrammable Memory Problem

Repair Processes :

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. Check to make sure they are not burnt or corroded. If in doubt, get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed.

Process Tips

Diagnostic trouble code C0129 Fiat 25 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 C0129 Fiat 25.

Fortunately, C0129 Fiat 25 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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