U029B Diagnostic Trouble Code

U029B 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 U029B diagnostic trouble code may include:

The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Faulty PCM
If the DPF is not cleared the ECU will revert to the "Limp Home Mode" until the situation is corrected
Diminished fuel efficiency

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.
Fuel with a large percentage of sulfur will clog the DPF quickly

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. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code U029B 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 U029B.

Fortunately, U029B is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U029B Trouble Code For Specific Cars

U029B Porsche Mega Fuel Pump Secondary Circuit Malfunction
U029B Abarth Monotipo A/C Evaporator Air Temperature Circuit High
U029B Suzuki Ignis Microphone Input Signal Circuit Open
U029B Nissan Figaro Clutch position ckt short to ground
U029B Volkswagen Gol Ride Control LR Shock Actuator Circuit Open
U029B Vauxhall Firenza Pressure Control Solenoid A Control Circuit / Open
U029B Leyland Marina Throttle Control Unit Detected Loss of Return Spring