U0028 Diagnostic Trouble Code

U0028 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 U0028 diagnostic trouble code may include:

Poor acceleration
Cherry red hot catalytic converter
Possible spark knock (detonation / pre-ignition)
Rich or lean exhaust

Possible Causes :

Faulty IMRC actuator relay (if equipped)
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
A plugged converter will cause of host of driveability problems as well as set this code. A severely plugged converter will result in the inability to increase rpm when under load. Look for a code such as P0421 -- catalytic converter efficiency below threshold if the converter indicating a faulty converter.

Repair Processes :

Look for rubbing, scraping, bare wires, worn spots or melted plastic connectors. Pull the connectors apart and carefully look at the terminals (the metal parts) inside the 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 U0028 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 U0028.

Fortunately, U0028 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U0028 Trouble Code For Specific Cars

U0028 Ford Econovan MAP/MAF Throttle Position Correlation
U0028 Ferrari 246 Input shaft speed signal missing/faulted
U0028 Volkswagen Sharan SCP (J1850) Communication Bus Fault
U0028 Renault Dauphine Gear Shift Position Circuit Low
U0028 Durkopp 20 Hp Immobilizer ID Does Not Match
U0028 Ford F150 Memory Set Switch Circuit Short To Battery
U0028 Peugeot 605 Electric Air Pump Primary Failure