1998 saturn check engine lite comes on gives codepo420&po573

CODE PO420 CATALYST SYSTEM LOW EFFICIENCY BANK 1 CONDITIONS.POSSIBLE CAUSE AIR LEAKS AT THE EXHAUST MANIFOLD OR IN THE EXHAUST PIPES.CONTINUOS ENGINE MISFIRE WEAK OR LOW COIL OUT PUT.FRONT HO2S AND REAR HO2S CONTAMINATED WITH FUEL OR MOISTURE.REAR HO2S IS LOOSE IN THE MOUNTING HOLE. CODE PO573 DID NOT SEE.

Code PO420 says the catalyst efficiency below threshold bank 1. The PCM copares switch rates between the front O2 sensors and the downstream catalyst moniters. The catylist moniters are often mistaken as O2 sensors, and they are, but that is not their job, or what they are called. By comparing the switch rates between the front (before cat) and rear (downstream of cat) the PCM knows if the cat is affecting the exaust, and how much it is affecting the exaust. If it sees little or no effect o the exaust gases that have passed through the cat, then it decides that the cat is not working anymore, ad sets a P0420, or a P0430, depending on which bank it is. To check this yourself, you will need to bring up data stream on your scanner, watch the upstream and downstream O2 parameters and see if they are following each other closely. If the cat is working right, you should see a fairly rapid switch rate, probably 5 or 6 times a minute on the front O2, but almost a flat line just above .5 volts on the rear. If the rear is switching often you proabably need a catalytic converter.




P0573-BRAKE SWITCH #1 CIRCUIT HIGH

When Monitored and Set Condition:

P0573-BRAKE SWITCH #1 CIRCUIT HIGH

When Monitored: Ignition on.

Set Condition: When the PCM recognizes Brake Switch #1 is stuck in the high/off position. One Trip Fault. Three good trips to turn off the MIL.

POSSIBLE CAUSES:

GOOD TRIP EQUAL TO ZERO

BRAKE LAMP SWITCH OPERATION

(K29) BRAKE SWITCH #1 SIGNAL CIRCUIT OPEN

(V32) BRAKE SWITCH #2 SIGNAL CIRCUIT SHORTED TO GROUND

GROUND CIRCUIT OPEN

Code po573 is cruise control / brake switch circuit A circuit voltage high PO420 catalyst system below threshold, po573 is probably a bad brake circuit / switch problem, PO420 is a bad catalatic convertor for bank 1