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.
1994 Porsche 911 Speedster, AutomaticFACTORY OEM SERVICE PROCEDURE
Code 1121: MAF Sensor
- Voltage Supply: Connect DVOM between ground and terminal No. 3 of MAF sensor wiring harness connector. See Fig 1 . Turn ignition on to check voltage supply to sensor. If reading is 4.7-5.3 volts, go to next step. If voltage is not 4.7-5.3 volts, check Blue/Green wire back to DME control unit.
- Voltage Drop: Disconnect air filter hose. Using jumper wires, connect terminal No. 3 of MAF sensor wiring harness connector to terminal No. 3 of sensor, and connect terminal No. 4 of wiring harness connector to terminal No. 4 of sensor.
- Connect DVOM between ground and MAF sensor terminal No. 2. Turn ignition on to check voltage drop across sensor. With MAF sensor plate closed, reading should be 250-260 millivolts.
- Using screwdriver handle, press MAF sensor plate to full throttle position. Reading should gradually increase to about 4.6 volts. If voltage values are incorrect, replace MAF sensor.
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.