C3121 Mitsubishi Sigma Diagnostic Trouble Code

C3121 Mitsubishi Sigma code definition:
C3121 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code for Mitsubishi Sigma.

C3121 Mitsubishi Sigma 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. As you drive and when specific conditions are slowly met, the vapors will gradually purge from the charcoal canister and will get burned within your engine.

Symptoms

Symptoms of a C3121 Mitsubishi Sigma diagnostic trouble code may include:

Fuel pressure too high
Diminished fuel efficiency
Rich or lean exhaust
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.
Faulty IMRC actuator relay (if equipped)

Common Misdiagnoses

Control Module Throttle Actuator Position Performance Problem
Air Conditioning (A/C) Clutch Feedback Circuit High Voltage Problem
Cruise Vehicle Speed/Set Speed Difference Too High Problem
Kick-Down Switch Failed Short Problem
Park/Neutral Postion (PNP) Switch Circuit Engine Torque Signal Circuit Problem

Repair Processes :

Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness. Oxygen sensors signal the engine management computer the amount of oxygen present in the exhaust, which is used in determining and controlling the fuel ratio. It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem.

Process Tips

Diagnostic trouble code C3121 Mitsubishi Sigma 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 C3121 Mitsubishi Sigma.

Fortunately, C3121 Mitsubishi Sigma is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.