U029B Leyland Eight Diagnostic Trouble Code

U029B Leyland Eight code definition:
U029B is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Leyland Eight.

U029B Leyland Eight shows up when there's an electrical problem that causes the fuel volume regulator to malfunction and open. It's quite an unusual problem and likely intermittent. The PCM then uses this data to provide the right strategies for the fuel delivery and ignition timing of the engine.

Symptoms

Symptoms of a U029B Leyland Eight 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
Place of U029B in engine

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

Common Misdiagnoses

  1. Crankshaft Position Sensor Circuit Performance Problem
  2. TP Sensor Learn Not Complete Problem
  3. Low Coolant Circuit Problem
  4. Cruise Control System - Vehicle Accel Too High Problem
  5. Kick-Down Switch Failed Short Problem

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 Leyland Eight 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 Leyland Eight.

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

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