Test FC-14A - Left O2S Stays Below Center (Lean) (DTC 51)

NOTE: For connector terminal identification, see CONNECTOR IDENTIFICATION . For appropriate wiring diagram, see WIRING DIAGRAMS at end of article.

Using DRB-II, set engine speed to 1500 RPM. Read left O2 sensor voltage. If left O2 sensor voltage is always more than 0.5 volt, go to step 3). If left O2 sensor voltage is always less than 0.5 volt, go to next step.
If LEFT O2S STAYS BELOW CENTER (LEAN) fault is not in memory, replace leaking injector for left intake manifold bank. Perform TEST VER-2. If LEFT O2S STAYS BELOW CENTER (LEAN) fault is in memory, a condition causing engine to run lean in all cylinders is indicated. Go to TEST NF-1A.
At this time, the condition required to set fault is not present. LEFT O2S STAYS BELOW CENTER (LEAN) fault sets if sensor signal stays less than 0.5 volt without changing for more than 8 minutes. Possible causes are: major vacuum leak, low fuel pressure, other engine sensor calibrations, ignition system failure, O2 sensor failure, or fuel contamination. Go to TEST NF-1A.