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Ron, ASE Certified Technician
Category: Mazda
Satisfied Customers: 36081
Experience:  35 years as a automotive tech
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96 Miata throwing PO 135. Installed new upstream O2 sensor,

Customer Question

96 Miata throwing PO 135. Installed new upstream O2 sensor, get same code.
I know one possible cause, but I can't check it. O2 sensor has a fuse that can blow under certain conditions, but I can't find out where it is located.
Submitted: 1 year ago.
Category: Mazda
Expert:  Ron replied 1 year ago.

Hello, my name is ***** ***** I am a professional here at Justanswer. Thank you for your question and I will assist you with your concern.

Since the HO2S sensor is new then the next step would be to check the circuit to it from the ECM (computer). I have enclosed the test steps to do this in the link below. Run through them and this should help you determine the cause. Both the upstream HO2S and down stream share the same power source to the problem is not likely a fuse.

See the ECM system wiring diagrams in the links below for testing reference as well.