U1127 Diagnostic Trouble Code

U1127 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 U1127 diagnostic trouble code may include:

Engine surge
Blown fuse (if applicable)
Lack of power
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.
Rarely - faulty Powertrain Control Module (PCM-programming required after replacement)

Repair Processes :

Once located, visually inspect the connectors and wiring. Look for rubbing, scraping, bare wires, worn spots or melted plastic connectors. 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. 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.

Process Tips

Diagnostic trouble code U1127 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 U1127.

Fortunately, U1127 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U1127 Trouble Code For Specific Cars

U1127 Subaru 1400 Lateral Accelerometer Sensor Circuit Open
U1127 Matra-simca M Transmission Over Temperature Condition
U1127 Alta 1.5-litre Air Bag Passenger Inflator Circuit Resistance Low on Squib
U1127 Volkswagen Golf 3 Ride Control LR Shock Actuator Circuit Short To Ground
U1127 Toyota Matrix Optical Sensor System Failure
U1127 Skoda Felicia Kickdown Relay Hold Circuit Fault
U1127 Paterson Sedan Driver Sliding Door Ajar Circuit Short to GND