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Been getting the P0133 code on and off for a while. Diodes test failed multiple times so I definitely need a new alternator. Could a bad alternator throw other codes? As you can see, the P0133 code says, "O2 sensor circuit slow response." If the alternator is failing to get electricity to the sensor, it'd throw the code right? Maybe same for the U1262? What are your opinions
 

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The O2 sensor code is for a dying sensor or vacuum leak, they switch high/low much slower when they are dying. They make their own power so the alt theory is wrong. Only power going there is from the heater circuit and that would be a different dtc.

The load input error may be tied to the alt harness, a communication issue between PCM and alt.
 

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Codes are created by your car's computer. Computers require stable, clean power to operate properly. So "Yes, a computer powered by a non-stable, dirty power supply could produce bogus codes." If you know you have a bad alternator:
-have the alternator rebuilt
-have the battery properly charged and THEN tested
- check all battery/alternator connections to make sure they are clean and tight. No corrosion!
- Check all ground connections to make sure they are also clean and tight.
- clear your computer codes, see what returns, then diagnose accordingly.
 

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Definitely go with what Milton said.

If alternator has/is dying, then codes cannot be relied upon to tell you anything. Fix alt first.

Also, if your battery has run down during all of this, don't use new alt to charge it. Charging a dead battery with alt can ruin the new alt...use a battery charger.
 

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Good point and X3 to add to those guys, the PCM can spout nonsense codes without adequate power to it....................
 
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