Little help with DTC after changing primary O2 sensors.

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03-14-2007, 08:22 PM

HIS4

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Little help with DTC after changing primary O2 sensors.

I was previously getting a high resistance DTC on both primary O2 sensors. I replaced both of them with Zoldmans from Vast. About a week after I changed the primary O2 sensors I got this DTC

16805 - Warm Up Catalyst; Bank 1: Efficiency Below Threshold

P0421 - 35-10 - - - Intermittent

What could this be now?

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03-14-2007, 08:27 PM

rktskicar

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It could be time for new cats or if you have aftermarket cats then can happen when cold outside

and you let your car run for awhile while cold.

Bruce

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03-14-2007, 08:30 PM

HIS4

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Hmm, that sucks. I'm running stock cats and stock exhaust.

I guess now would be a good time for aftermarket exhaust and DPs.

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03-14-2007, 08:31 PM

HIS4

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Do you think running rich from having bad primary O2s would cause the cats to die?

Or does it have anything to do with ethanol additives they're putting in the fuel. Hawaii just started mandatory ethanol (I think it's E15) last April.

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