1989 HONDA PRELUDE
425,000 MILES
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O2 trouble codes. Slight surging (speed) on highway
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Hello, I recently replaced the original never-changed 02 sensors. No prior problem, mechanic friend said they should be replaced.

Check engine light comes on after 2-5 minutes and codes 1 and 2 flash on the ECU. Slight surging on the highway at 65 mph but no discernible rhythm or pattern to it. Random.

Checked sensors for contamination but none that I can see. (Can send pic.) Connections seem ok. Do not know how to check output from sensors.

Wrong or bad aftermarket sensors? (There are two; both on exhaust manifold.)

Replaced EGR valve yesterday after trouble code 12 that I ignored for many months. Seems to be more power now than before.

Starts, idles fine.

Richard
Nov 28, 2012 at 5:39 PM
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KHLOW2008
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Some after market O2 sensors do not work. If original O2 sensor was not showing any trouble code, rreinstall and test. If the part is not bad, why do you need to replace it?
Nov 28, 2012 at 6:13 PM