C1421 Diagnostic Trouble Code

C1421 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a C1421 diagnostic trouble code may include:

Excessive exhaust leak
Hesitation upon acceleration
Malfunction Indicator Lamp (MIL) illuminated
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected

Possible Causes :

A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
Faulty IMRC actuator relay (if equipped)
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.

Repair Processes :

Now, clear the codes and test-drive the vehicle to see if the code is reset. Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code C1421 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 C1421.

Fortunately, C1421 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C1421 Trouble Code For Specific Cars

C1421 Opel Grandland X Dim Panel Increase Input Circuit Open
C1421 Toyota Dyna O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 1)
C1421 Suzuki Sx4 S-cross Mirror Driver Switch Assembly Circuit Short To Ground
C1421 Reliant Scimitar Gate Select Position Circuit [senses left / right position]
C1421 Rover Range Rover Ignition Cylinder Sensor Ground Short
C1421 Volkswagen Export Ride Control LF Shock Actuator Circuit Open
C1421 Mitsubishi Aspire Audio Front Control Module (ACM) is Not Responding