Datsun310Guy UltimaDork
8/22/19 9:01 p.m.

210,000 miles - check engine light,

How do I easily check upstream O2 sensor, downstream O2 sensor, or Cat Convertor?



Toebra Dork
8/23/19 8:23 a.m.

O2 sensor can probably be checked with an ohmeter.  You need to know what it is supposed to read though.

Nugi Reader
8/26/19 9:31 a.m.

Ghetto fix: o2 sensor spacer aka antifouler.

Real fix, 1. replace o2 sensor. 2. Yell expletives when its still there and replace cat. 



alfadriver MegaDork
8/26/19 9:49 a.m.

If you have a PID recorder, you can record it- and check that the signals for both sensors look reasonable.  If things were broken in the sensors which would be a resistance change, the ECU would note that well before the catalyst efficiency code.

And before throwing parts at it, I'd spend the money on an OBDII recorder.  As you can use that on other cars.

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