C0258 Triumph Stag Diagnostic Trouble Code

C0258 Triumph Stag code definition:
C0258 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code for Triumph Stag.

C0258 Triumph Stag is described as Intake Air Temperature (IAT) Circuit Malfunction. It's actually a general trouble code for a problem on IAT electrical circuit sensor, as it sends incorrect voltage input signals to the PCM. As you drive and when specific conditions are slowly met, the vapors will gradually purge from the charcoal canister and will get burned within your engine.

Symptoms

Symptoms of a C0258 Triumph Stag diagnostic trouble code may include:

Faulty or damaged wiring
The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
Poor fuel economy
Hesitation upon acceleration

Possible Causes :

Some aftermarket accessories and performance modifications
A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.

Common Misdiagnoses

Exhaust Gas Recirculation System Valve 1 Problem
BBV Sensor Circuit Low Voltage Problem
Transmission Engaged At High Throttle Angle Problem
Cruise Inhibit Control Circuit Problem
TFP Valve Position Switch-Drive Without Drive Ratio Problem

Repair Processes :

Oxygen sensors signal the engine management computer the amount of oxygen present in the exhaust, which is used in determining and controlling the fuel ratio. 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 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.

Process Tips

Diagnostic trouble code C0258 Triumph Stag 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 C0258 Triumph Stag.

Fortunately, C0258 Triumph Stag is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.