Diagnostic Method

2014 Subaru Impreza Sport LimitedSECTION Diagnostic Method
WARNING: This page is about a different car, the 2014 Subaru XV Crosstrek. However, it is still accessible from the selected car via links, so may be relevant.

Detect the trouble by calculating the time from the completion of the fuel cut to the beginning of the rear oxygen sensor voltage starting to rise.

Fig 1: Rear Oxygen Sensor Air Fuel Ratio Voltage Graph
G09477562Courtesy of SUBARU OF AMERICA, INC.
  • Abnormality Judgment 

Judge as NG when the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria Threshold Value
The number of times that the rear oxygen sensor voltage changed to 0.3 V after the fuel cut has completed (time counter) > 3750 time(s)

Time Needed for Diagnosis:  32 ms x 3750 time(s)

Malfunction Indicator Light Illumination:  Illuminates when malfunction occurs in 2 continuous driving cycles.

  • Normality Judgment 

Judge as OK and clear the NG if the following conditions are established.

JUDGMENT VALUE

Malfunction Criteria Threshold Value
The number of times that the rear oxygen sensor voltage changed to 0.3 V after the fuel cut has completed (time counter) ≤ 3750 time(s)

Time Needed for Diagnosis:  32 ms x less than 3750 time(s)

RENDER: 1.0x

NO RELATED

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.