Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
1993 Subaru Justy BaseFACTORY OEM SERVICE PROCEDURE
Code 26: Air Temperature Sensor
NOTE:
Refer to illustration for ECU connector and terminal identification. See Figure
.
- Turn ignition on. Backprobe ECU connector F121 and measure voltage between terminals No. 6 and 1 and between terminals No. 6 and 2. If both voltage readings are 0.15-4.85 volts, check for poor ECU connector contact. Repair connector and/or wiring harness as necessary. If either voltage reading is not 0.15-4.85 volts, go to next step.
- Turn ignition off. Disconnect air temperature sensor. Measure resistance between air temperature sensor terminals. See the AIR TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS
table. If resistance is as specified, go to next step. If resistance is not as specified, replace air temperature sensor.AIR TEMPERATURE SENSOR RESISTANCE SPECIFICATIONS
Temperature °F (°C) Ohms 68°F (20°C) 2000-3000 176°F (80°C) 270-370 - Disconnect ECU connectors. Measure resistance between ECU connector F121, terminal No. 6 and terminal No. 2 (White/Blue wire) of air temperature sensor connector. Measure resistance between ECU connector F121, terminal No. 1 and terminal No. 1 (Black/Green wire) of air temperature sensor connector. Also, measure resistance between ECU connector F121, terminal No. 2 and terminal No. 2 (Black/Green wire) of air temperature sensor connector. If all resistances are less than one ohm, go to next step. If any resistance is more than one ohm, repair connector and/or wiring harness as necessary.
- Measure resistance between ground and ECU connector F121, terminal No. 6. If resistance is infinite, check for poor ECU connector contact. Repair connector and/or wiring harness as necessary. If connector and wiring harness are okay, replace ECU. If resistance is not infinite, repair connector and/or wiring harness as necessary.
Factory Service Tools
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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.