C0798 Diagnostic Trouble Code

C0798 is a kind of OBD-II Diagnostic C-Chassis 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 C0798 diagnostic trouble code may include:

Excessive exhaust leak
Hesitation upon acceleration
Malfunction Indicator Lamp (MIL) illuminated
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.
Low fuel pressure caused by a clogged filter, failing fuel pump, failed fuel pressure regulator or clogged or leaking injectors.

Repair Processes :

Pack the connector cavity with dielectric silicone compound (same stuff they use for light bulb sockets and spark plug wires) and reassemble. 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. 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 C0798 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 C0798.

Fortunately, C0798 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C0798 Trouble Code For Specific Cars

C0798 Daewoo Musson Gauge Driver Circuit Fault
C0798 Dauer Eb HO2S Heater Control Circuit High (Bank 2 Sensor 3)
C0798 Nissan Primastar Crankshaft Position Camshaft Position Correlation (Bank 1 Sensor A)
C0798 Peugeot 208 EGI Functionality Test Failed
C0798 Packard 12 Downshift Switch Circuit
C0798 Pontiac 28 Exhaust Not Warm, Downstream O2 Sensor
C0798 De Tomaso Guara HPU (Hydraulic Pump Unit) Pressurisation Failure