U1838 Diagnostic Trouble Code

U1838 is a kind of OBD-II Diagnostic U-Network 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 U1838 diagnostic trouble code may include:

Possible spark knock (detonation / pre-ignition)
Poor fuel economy
The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

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.
Defective ECU strategies or components will prevent proper regeneration

Repair Processes :

It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem. Look at the plug wires to make sure they are not burnt or laying on the exhaust. 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.

Process Tips

Diagnostic trouble code U1838 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 U1838.

Fortunately, U1838 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U1838 Trouble Code For Specific Cars

U1838 Honda Element Pressure Transducer Redundant / Secondary Input Circuit Failure
U1838 Renault Fregate Glow Plug Circuit High Input (Bank #1)
U1838 Bmw 2500 Camshaft Position Sensor Circuit Range/Performance
U1838 Dodge Venom Ignition Tach Circuit Short To Battery
U1838 Mclaren F1 A/C Refrigerant Pressure Sensor Circuit Range/Performance
U1838 Steyr G-series Lamp Tail Output Circuit Short To Battery
U1838 Aixam Evolution ABS Outlet Valve Coil LR Circuit Short To Battery