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ron
01-08-1999, 02:24 PM
what's the procedure for testing if your O2 sensor is ok? I am starting to think mine might need replacement. What are the tell-tale symptoms? I know it's outlined in the Bentley manual, but i haven't been able to locate mine since i moved. TIA<p>ron<br>89 e34

William Ray
01-08-1999, 03:52 PM
The most prevalent syptom is that your "check engine" light comes on. Then it will store a DME code for a bad O2 sensor.<p><i>: what's the procedure for testing if your O2<br> sensor is ok? I am starting to think mine might need replacement. What are the tell-tale symptoms? I know it's outlined in the Bentley manual, but i haven't been able to locate mine since i moved. TIA<p>: ron<br>: 89 e34 <p></i>

TBM
01-11-1999, 12:49 AM
The procedure below is a condensed Bently Manual version.<br>Will need a voltmeter capable of measuring 0~12.0 VDC and some gloves. <br>Start the car and let it idle for a few minutes.<br>The 4-pin connector is located in the right hand rear of the engine compartment, on the firewall next to the electronics box. With the engine running, pull back the rubber boot on the back side of the connector (sensor side) to expose the back side of the wire terminals. There will be a grey wire, black wire, and two white wires. The white wires are the O2 heater wires and should read battery voltage. The grey and black wires are the O2 signal wires. The voltage should be fluctuating between 0.2~0.8 VDC. If the sensor passes both of these tests, it doesn't mean it is OK. As the sensor gets older, its ablity to quickly change the mixture diminishes. AS the Bentley Manual reads, the only true way to test is through an exhaust gas analyizer. I don't have the analyzer, so I replace mine every 60~70k miles. I don't use the Bosch original ($165), instead, I use a 4-wire Ford unit ($70) which comes with wire connectors and heat shrink tubing to connect it to your existing plug. Check out www.mesaperformance.com. These guys can set you up with the correct generic unit. Hope this helps:-).<p>TBM<br>89 525i<br>85 325e<br>


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