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.
SYS.OK|MANUAL.DBβ LIVE
HOMESERVICE MANUALSMAZDA1999626 ES, 2.5 D, STANDARDREPAIR AND DIAGNOSISENGINE PERFORMANCETESTING & DIAGNOSISENGINE CONTROLS - SELF-DIAGNOSTICSDIAGNOSTIC TESTSDTC P0122: THROTTLE POSITION (TP) SENSOR LOW INPUTCONDITION
1999 Mazda 626 ES, 2.5 D, Standard
DTC P0122: Throttle Position (TP) Sensor Low Input: Condition
1999 Mazda 626 ES, 2.5 D, StandardSECTION Condition
This code indicates TP signal is less than self-test minimum of 0.17 volt. Possible causes for this fault are:
- TP sensor not seated correctly.
- Faulty TP sensor.
- Open TP or VREF circuit.
- TP circuit shorted to SIG RTN or PWR GND.
- Faulty PCM.
- Attempt To Generate DTC P0123
Ensure freeze frame data is recorded. Turn ignition off. Disconnect TP sensor wiring harness connector. Inspect for damage and repair as necessary. Connect jumper wire between VREF and TP terminal at TP wiring harness connector. Turn ignition on. Access TP PID on scan tool. If PID voltage is greater than 4.60 volts, replace TP sensor and repeat QUICK TESTΒ . If PID voltage is 4.60 volts or less, remove jumper wire and go to next step. If scan tool is unable to access TP PID, go to step Β 4. - Check VREF Circuit Voltage
With TP sensor disconnected, turn ignition on. Measure voltage between VREF and SIG RTN terminals at TP sensor wiring harness connector. If voltage is 4-6 volts, go to next step. If voltage is not 4-6 volts, reconnect sensor and repair open VREF circuit. - Check TP Circuit Resistance
Turn ignition off. Leave TP sensor disconnected. Disconnect PCM 104-pin connector. Inspect connector for damage and repair as necessary. Install Breakout Box (014-00950), leaving PCM disconnected. Measure resistance between test pin No. 89 (TP) and TP terminal on TP sensor wiring harness connector. If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open in TP circuit. - Check TP Circuit For Short To SIG RTN Or PWR GND
Leave ignition off and TP sensor disconnected. Measure resistance between test pin No. 89 (TP) and test pins No. 91 (SIG RTN), 24 and 103 (PWR GND) at breakout box. If any resistance is less than 10 k/ohms, repair TP circuit short to SIG RTN or PWR GND and repeat QUICK TESTΒ . If both resistances are 10 k/ohms or more, replace PCM and repeat QUICK TESTΒ .
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- β’ You smell fuel, burning insulation, or see smoke.
- β’ Brakes feel soft, pull hard to one side, or make grinding noises.
- β’ The engine overheats, stalls repeatedly, or misfires under load.
- β’ You are missing required tools, torque specs, or safe lifting equipment.
- β’ You are not confident in the next step or safety outcome.