Hyundai XG30/300 This car has problem with close loop, work one minute and later the scanner show Open Loop Fault, I changed O2 sensor and Temperature sensor.

Marvin

• 85242 Answers
• Posted on Jan 14, 2009

SOURCE: I get a DTC P0133 code on my 1998 Ford Explorer V8

it may be a defective O2 sensor here is th difinition:
P0133 - Heated Oxygen Sensor (HO2S) Slow Response Bank 1 Sensor 1 , this is the sensor on the side of the engine that #1 cylinder is on, it is the sensor before the cat.

SOURCE: Rough Idle on start up: faulty O2 sensor?

try coolant temperature sensor

SOURCE: ECM switches from closed loop to open loop at idle after warmup

WHEN ENGINE GOES CLOSED LOOP TO OPEN LOOP.YOU HAVE A RICH FUEL MIXTURE.YOU HAVE A VACUUM LEAK.BY YOU HAVING ROUGH IDLING.AND A HIGH MILEAGE ENGINE I WOULD DO A COMPRESSION TEST OR CYLINDER LEAK DOWN. CHECK FOR LEAKING VALVES AND LOW COMPRESSION .THEY BOTH WILL CAUSE ENGINE TO IDLE ROUGH CAUSE MISFIRE.CAUSE OPEN LOOP CONTAMINATE HO2 SENSOR CAUSE A RICH FUEL MIXTURE.

SOURCE: B0012 SAYS FRONTAL PASSENGER DEPLOYMENT LOOP. WHAT

B0012 is a fault on the DRIVERS side, you sure you read the code right?
If it is a B0012 then any of the wiring could be suspect the coil or the air bag it's self. I have seen a couple of cars coming with this code and I found the wires coming out of the air bag in the steering wheel to be rubing where they go through the steering wheel into the colume, may want to check there first.
Report back if the code is something else so we can try and assist you.

SOURCE: I've got a CEL P0420 code on a 96 Civic.

This code can mean any of the following and not a necessarily bad catalytic converter

A code P0420 may mean that one or more of the following has happened:

• Leaded fuel was used where unleaded was called for
• An oxygen sensor is not reading (functioning) properly
• The engine coolant temperature sensor is not working properly
• Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe
• Retarded spark timing
• The oxygen sensors in front and behind the converter are reporting too similar of readings

• Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
• Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
• Inspect the downstream heated oxygen sensor (HO2), replace if necessary
• Replace the catalytic converter