C1638 Diagnostic Trouble Code

C1638 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 C1638 diagnostic trouble code may include:

Reduction in engine performance, especially at low RPM levels
Vacuum leak on the engine
Diminished fuel efficiency
Rich or lean exhaust

Possible Causes :

The Mass Airflow sensor will also cause this problem. Mass Airflow circuit malfunction.
Fuel with a large percentage of sulfur will clog the DPF quickly
Dirty air cleaner element Damaged DPF

Repair Processes :

Look for damage to the tank indicating impact that may have damaged the fuel pump or sender. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed. If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs.

Process Tips

Diagnostic trouble code C1638 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 C1638.

Fortunately, C1638 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C1638 Trouble Code For Specific Cars

C1638 Ferrari 412 Intake Air Temperature Sensor 2 Circuit Range/Performance
C1638 Hyundai Concept SCP (J1850) Communication Bus Fault
C1638 Volkswagen Touran I SCP (J1850) Invalid or Missing Data for Audible Warnings
C1638 Ford Desert Manifold Absolute Pressure/Barometric Pressure Circuit Malfunction
C1638 Bertone 4x4 Brake Fluid Level Sensor Input Short Circuit To Ground
C1638 Dkw Reichklasse Ignition Coil - Cylinder 1 - Early Activation Fault
C1638 Alfa Romeo Gta Air Assisted Injector Control Range/Performance