U0129 Diagnostic Trouble Code

U0129 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 U0129 diagnostic trouble code may include:

Fuel pressure too low
Rich or lean exhaust
Diminished fuel efficiency
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.
Faulty IMRC actuator/sensor

Repair Processes :

Check to make sure they are not burnt or corroded. If in doubt, get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed. Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code U0129 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 U0129.

Fortunately, U0129 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

U0129 Trouble Code For Specific Cars

U0129 Toyota 2000 Neutral Switch Circuit Malfunction
U0129 Renault 14 Gear 1 Incorrect ratio
U0129 Honda Pilot Ii Rear Doppler Sensor Circuit Failure
U0129 Rickenbacker 8 HO2S Transition Time Ratio Sensor 1
U0129 Renault Kangoo Glow Plug/Heater Indicator Circuit Malfunction
U0129 Lanchester 30 Speed Control Unable to Hold Speed
U0129 Honda Torneo Reverse Mirror Output Circuit Failure