Smog problem - Should this vehicle have an O2 sensor ? 1985 Subaru GL wagon 1.8L 5 speed


Asked by Feb 17, 2015 at 01:27 PM

Question type: Maintenance & Repair

Vehicle easily passed smog test two years ago; now fails due to quite high NOx.  Catalytic convertor replaced one year ago. EGR is 2 years old and functions normally.  Engine idle is remarkably smooth, but exhaust system now runs unusually hot at highway RPM; timing at idle is correct.  There is no O2 sensor.  Question: should there be an O2 sensor on this vehicle?

5 Answers


Yes, it's OBD I. Excessive NOX is usually caused by the engine running too hot or too lean. HTH. -Jim


Here's a picture of the oxygen sensor for your Subaru


Thanks!!! Clarification from 3Vern: Right now O2 sensor is missing from vehicle - if it ever had one. Subaru company district engineer says it never had an O2 sensor. My question : Is he correct? (Vehicle = 1985 Subaru GL wagon 1.8L 5 speed) Second question : Jim - what are the abreviations OBD and HTH ?

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80,345 shows a listing for all 3 of the 1.8L engines that were available for your '85 Subaru GL. So I'd say yes, it's supposed to have one. The abbreviation OBD stand for OnBoard Diagnosis. The abbreviation HTH stands for hope this helps. Do you have a "check engine" or "service engine soon" light? If so, that's a sure sign that you're supposed to have one. The oxygen sensor "sniffs" the exhaust gases and then the computer adjusts the air to fuel mixture to maintain a 14 to 1 ratio. This is done constantly while you're driving. The 14 to 1 ratio maintains fuel economy, performance, and emissions all within optimum levels. HTH. -Jim


Thanks again!!! More clarification from 3Vern: There is no 'check engine' or 'service engine soon' light. I initially assumed the O2 sensor was not reinstalled when the catalytic convertor was replaced one year ago. But then I could not find an appropriate electrical plug anywhere in the wiring harness to plugin a wire from an O2 sensor - does anyone have a wiring diagram or is one available somewhere online? (vehicle: 1985 Subaru GL wagon 1.8L 5 speed - not the turbo) - 3Vern

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