U1143 BMW Fault Code

Description:

The Throttle Position sensor signals the Engine Control Module as to the current position of the engine throttle valve.
The current throttle valve opening is based on the driver's input from the gas pedal.

The ECM uses the information from this sensor to help calculate fuel delivery and spark timing.

U1143 Code Symptoms :

The rule of U1143 code when it comes to emissions-related vehicle repair is that any modification that changes the vehicle from a certified configuration to a non-certified configuration is considered tampering: this applies to both vehicle owners and repair facilities and is, therefore, a Federal offense. Replacing a catalyst with a straight pipe is one traditional example of U1143.

Likewise, overriding the OBD system through the use of high-tech defeat devices or non-certified computer chips, for example, would also be considered tampering. The OBD system may, however, be repaired back to its original certified configuration with certified performance chips or appropriate aftermarket parts.

Diagnosis And Repairing U1143

Parts or components should not be replaced with reference to only a U1143 DTC. The vehicle service manual should be consulted for more information on possible causes of the fault, along with required testing.

How to fix U1143 code ?

• Faulty Air Flow Meter
• Faulty oil control valve (OCV)
• Faulty front heated oxygen sensor
• Damaged VCT phaser

A good starting point in your diagnosis is checking all system fuses and fusible links. This can be done using the BMW DVOM on the voltage setting. You will want to test the fuses with circuits loaded.

Some fuses will appear normal until a load is placed on their respective circuit; at which point they will fail. This has been the cause of many 'phantom malfunctions'. Consult your vehicle information source for fuse and fusible link locations. If all fuses are in working order, you may want to check TCM relay operation by swapping identical relays. Usually the horn relay, starter relay, fuel pump relay, air conditioning clutch relay, and controller relays are similar enough in design to swap for diagnostic purposes.