Chevrolet Prizm:

Check engine codes, how to fix

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# 1  9/9/2013 9:53 PM

brucher
New member
Registered: 9/9/2013
Posts: 1

Check engine codes, how to fix

Keep getting 3 codes. One has to do with oxygen sensor, the other 2 are a mystery to me how to remedy.
99 Prizm AT
Codes: 420-01 (O2 sensor, which one, upstream or downstream? 441-02 and 446-03.  Where is the sensor to replace?

I am handy and do most repairs, this one has me mystified.

Any help/guidance out there?

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# 2  9/10/2013 6:34 PM

TechHelp2
Administrator
Registered: 11/24/2009
Posts: 1299

Re: Check engine codes, how to fix

The PO420 is described as low catalyst efficiency.

You need to determine if the oxygen sensor is bad or if the catalytic converter is faulty. To properly diagnosis you would need a scanner to monitor the activity of the upstream O2 sensor and the down stream O2 sensor to determine if it is the sensor or the catalytic converter is bad. The activity of the upstream O2 sensor should be more responsive than the down stream sensor which will show hardly any activity. This will show a catalytic converter working properly.

If the activity of both O2 sensors is almost the same then it would show a faulty catalytic converter causing the check engine light to illuminate.

The things to look for before you change the O2 sensor or the catalytic converter are:

Make sure there are no exhaust leaks; this can cause false readings of the O2 sensors.

Check the catalytic converter for any rattling (loose catalyst), dents, and holes.

Check the O2 sensors for any damage to the wires, plugs and or connectors inside the plug and if the sensor is loose.

To determine the proper o2 sensor you would need the scanner. Most cases but not always the down stream (the one after the catalytic converter) sensor is usually faulty. Don't change the o2 sensor with out properly diagnosing the problem first. If you don't you could spend the money on a part you don't need.

PO441 is the EVAP (Evaporative emission system) has no flow during purge.

The pressure indicated in the EVAP canister does not drop during purge control (EVAP canister purge solenoid valve is ON).

The pressure indicated in the EVAP canister remains very low when compared to atmospheric pressure during purge cut off (EVAP canister purge solenoid valve is OFF).

The DTC P0441 diagnostic checks for EVAP system leaks on the purge side of the EVAP system. A fault in any of the EVAP system components, except the fuel tank and filler pipe, can cause a DTC P0441 to set. Check for any of the following conditions:

A faulty fuel tank pressure sensor
A faulty EVAP canister purge solenoid valve
A faulty EVAP pressure switching solenoid
A faulty or leaking EVAP canister
Damaged or leaky hoses, lines, or fittings
A faulty or leaking fill limiter vent valve (FLVV)

The PO446 is the EVAP (Evaporative Emission system) vent system performance.

P0446 can be caused by a faulty EVAP canister. An EVAP canister that has released carbon particles can cause the EVAP canister purge solenoid valve to fail (leak) intermittently. Inspect the EVAP purge system for carbon contamination before returning the vehicle to service.

A faulty fuel tank pressure sensor
A faulty EVAP canister purge solenoid valve
A faulty EVAP pressure switching solenoid
A faulty or leaking EVAP canister
Damaged or leaky hoses, lines, or fittings
A faulty or leaking fill limiter vent valve (FLVV) For functional checks of the components listed above, Refer to EVAP Control System Diagnosis.


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