08 hyundai santa fe 2.7l

I have codes for cyl 1, 3, and 5 misfires, along with codes for injectors circuit 1, 3, and 5 voltage low. Besides a harness what would cause these all at the same time? I can clear the codes and they won’t come back unless the vehicle is driven for 20 plus miles.

RESPONSE

Hyundai Code P0300 – Random/Multiple Cylinder Misfire Detected

Hyundai Code P0300 Possible causes

– Faulty spark plug (s)
– Faulty ignition coil (s)
– Clogged or faulty fuel injector (s)
– Intake air leak
– Fuel injectors harness is open or shorted
– Fuel Injectors circuit poor electrical connection
– Ignition coils harness is open or shorted
– Ignition coils circuit poor electrical connection
– Insufficient cylinders compression
– Incorrect fuel pressure

The P0300 code means that a cylinder(s) is misfiring or is randomly misfiring. Start by checking for intake leaks, intake gaskets are common caused of multi-cylinder misfiring. If no leak are found the next step is to replace the spark plugs. If the problem persist more tests needs to be done to diagnose problem, see “Possible Causes”.

There is a factory technical service bulletin for the following Hyundai models:

Accent (MC)
2003-2006 SULEV Elantra (XD)
2004-2008 Tiburon 2.0L (GK)
Tucson 2.0L (JM)
Elantra (HD)
Elantra Touring (FD)
Genesis Coupe (BK)
Sonata (NF)
Santa Fe
Sonata (NF)
Santa Fe (CM)
Azera (TG)
Veracruz (EN)
Entourage (EP),
Genesis Coupe (BK)
Genesis Sedan (BH)Genesis Sedan (BH)

The bulletin provides information on how to inspect and diagnose problems related to the Oil Control Valve (OCV) used in Constant Variable Valve Timing (CVVT), if at any time the OCV is suspected as the caused of rough idling, poor acceleration, camshaft timing misalignment-related trouble codes, misfire-related trouble codes.

P0203 HYUNDAI – Injector Circuit Open – Cylinder 3

Possible causes
– Faulty fuel injector 3
– Fuel Injector 3 harness is open or shorted
– Fuel injector 3 circuit poor electrical connection
The P0203 is set if the Engine Control Module (ECM) is detects a low or high voltage drop or resistance at the injector 3.

Engine Control Module (ECM) checks the injectors circuit resistance and monitors the voltage drop during normal operation. The ECM will trigger the P0203 code when the resistance or voltage drop at the injector 3 is out of specifications.