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Home >> Mazda >> 2000 >> B3000 SX, Automatic >> Repair and Diagnosis >> Engine Performance >> Engine Control Systems >> Engine Controls Trouble Shooting (2 Of 5) >> Throttle Position (TP) Sensor Circuit Malfunction
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Throttle Position (TP) Sensor Circuit Malfunction

DTC P0121, P0122, P0123, P1120, P1121, P1124, P1125 DETECTION CONDITION AND POSSIBLE CAUSE

DTC P0121, P0122, P0123, P1120, P1121, P1124, P1125 THROTTLE POSITION (TP) SENSOR CIRCUIT MALFUNCTION
DETECTION CONDITION 
  • P0121 indicates a non-closed throttle position at idle.
  • P0122 indicates TP sensor signal is less than Self Test minimum of 0.17 V (3.42%).
  • P0123 indicates TP sensor signal is greater than Self Test maximum value of 4.65 V (93%).
  • P1120 indicates TP sensor signal falls between 0.17 and 0.49 V (3.42 and 9.85%). Which is below the closed throttle position range.
  • P1121 indicates TP sensor signal is inconsistent with MAF sensor signal.
  • P1124 indicates TP sensor's rotational setting and signal are not in the Self Test Range of 0.66 to 1.17 V (13.27% to 23.52%).
  • P1125 indicates TP sensor signal went below 0.49 V or above 4.65 V sometime during last 80 warm-up cycle
POSSIBLE CAUSE 
  • Binding or bent throttle linkage (P0121, P1124).
  • TP sensor not seated properly or tightened down (P0122, P0123, P1121, P1124).
  • Throttle plate below closed throttle position (P1124).
  • Throttle plate/screw misadjusted (P1124).
  • Damaged TP sensor (P0121, P0122, P0123, P1121, P1124).
  • Damaged PCM (P0122, P0123, P1124).
  • Air leak between MAF sensor and throttle body (P1121).
  • Damaged MAF sensor (P1121).
  • TP sensor loose pins (P1120).
  • Damaged throttle body (P0121).
  • Intermittent open or short in TP sensor (P1125).
  • Wiring concerns:
    • Frayed wires (P1120).
    • Corrosion on TP sensor, PCM or harness connectors (P1120).
    • VREF harness opens or shorts to TP sensor (P0122, P1120).
    • Open TP SIG circuit/TP circuit open to PCM (P0121, P0122).
    • Open SIG RTN harness circuit (P0121, P0123).
    • TP circuit short to GND (P0122).
    • TP circuit short to PWR (P0123).
    • VREF short to PWR (P0123).
    • VREF short to SIG RTN (P1120).
    • Poor continuity through TP sensor connectors or harness (P1125).
HINT  TP Sensor Description 
  • Linear type sensor.
  • Four throttle operating conditions are determined by the PCM from the TP sensor signal:
    • Closed throttle (idle or deceleration).
    • Part throttle (cruise or moderate acceleration).
    • Wide open throttle (maximum acceleration or de-choke on crank).
    • Throttle angle rate.
G03988114Courtesy of MAZDA MOTORS CORP.
G03988115Courtesy of MAZDA MOTORS CORP.
DTC P0121, P0122, P0123, P1120, P1121, P1124, P1125 INSPECTION

STEP INSPECTION ACTION
1
  • Was PCM Quick Test performed? 
 Yes For KOEO and KOER DTC P1124:
Go to step 2.
For DTC P1120:
Go to step 4.
For DTC P0123:
Go to step 9.
For Continuous Memory DTC P1124:
Go to step 9.
For DTC P0122:
Go to step 13.
For DTC P1121:
Go to step 17.
For DTC P1125:
Go to step 21.
For DTC P0121:
Go to step 23.
No Perform PCM Quick Test.
2 CHECK FOR DTC P1400 IN KOEO OR KOER SELF-TEST
  • Is KOEO or KOER DTC P1400 present with P1124? 
 Yes Go to DTC P1400.
See DIFFERENTIAL PRESSURE FEEDBACK EGR (DPFEGR) SENSOR MALFUNCTION .
No Go to next step.
3 CHECK FOR STUCK THROTTLE PLATE OR LINKAGE
  • Visually inspect the throttle linkage and throttle plate for binding or sticking.
  • Verify throttle plate and linkage is at closed throttle position.
  • Does the throttle move freely and return to closed throttle position? 
 Yes Go to step 9.
No Repair or replace as necessary.
Go to step 25.
4 DTC P1120: CHECK TP CIRCUIT FOR FRAYED WIRES OR CORROSION ON CONNECTORS
  • Visually inspect the TP sensor harness connector pins for corrosion.
  • Visually inspect the harness wires between the TP sensor and the PCM for insulation fraying and corrosion.
  • Is a fault present? 
 Yes Repair as necessary.
Go to step 25.
No Go to next step.
5 CHECK FOR STUCK TP SENSOR
  • Key ON, Engine OFF (KOEO).
  • Access TP V PID.
  • Slowly move throttle from closed throttle position to wide open throttle position and observe the TP V PID.
  • While operating the throttle, is the TP V PID reading below 0.49 V? 
 Yes Go to next step.
No Go to step 21.
6 CHECK VREF AND SIG RTN CIRCUIT TO TP SENSOR
  • Key OFF
  • Disconnect TP sensor.
  • Key ON, Engine OFF (KOEO).
  • Measure voltage between VREF and SIG RTN at TP sensor harness connector.
  • Is the voltage between 4.0 and 6.0 V? 
 Yes Go to next step.
No Restore vehicle and refer to TEST 1: VEHICLE REFERENCE VOLTAGE (VREF) .
7 CHECK TP CIRCUIT RESISTANCE
  • Key OFF.
  • Disconnect PCM.
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance of TP circuit between PCM test pin 89 and TP sensor harness connector.
  • Is the resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair corroded or open circuit.
Go to step 25.
8 CHECK TP SENSOR SIGNAL TO PCM
  • Connect PCM to Breakout Box and reconnect TP sensor.
  • Start engine and run at idle for 2 minutes.
  • Access TP V PID.
  • Slowly open the throttle from closed position while observing TP V PID.
  • Is TP V PID reading at any time between 0.17 to 0.49 V? 
 Yes Replace TP sensor.
Go to step 25.
No Rerun KOEO and KOER.
If DTC P1120 is still present, go to step 21.
9 DTC P0123 OR P1124: ATTEMPT TO GENERATE THE OPPOSITE THROTTLE POSITION ANGLE (VOLTAGE) PID READING
NOTE: An intermittent fault can cause a Continuous Memory DTC P0123.
If this code is still present after step 9 through step 12, go to step 21.
  • Key OFF.
  • Disconnect TP sensor.
  • Key ON, Engine OFF (KOEO).
  • Access TP V PID with NGS Tester.
  • Is TP V PID less than 0.17 V? 
 Yes Go to next step.
No Go to step 12.
10 CHECK SIG RTN CIRCUIT FOR OPEN
  • Key OFF.
  • Disconnect PCM.
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance of SIG RTN circuit between PCM test pin 91 and TPS connector.
  • Is resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair open circuit.
Go to step 25.
11 CHECK VREF AND SIG RTN CIRCUITS TO TP SENSOR
  • Key ON, Engine OFF (KOEO).
  • Measure voltage between VREF and SIG RTN at TP sensor harness connector.
  • Is the voltage between 4.0 and 6.0 V? 
 Yes Replace TP sensor.
Go to step 25.
No Restore vehicle and refer to TEST 1: VEHICLE REFERENCE VOLTAGE (VREF) .
12 CHECK TP CIRCUIT FOR SHORTS TO VREF OR VPWR IN HARNESS
  • Key OFF.
  • Disconnect PCM.
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance between PCM test pin 89 (TP) and PCM test pins 71 or 97 (VPWR).
  • Measure resistance between PCM test pin 89 (TP) and PCM test pin 90 (VREF).
  • Are both resistances greater than 10K ohms? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to step 25.
No Repair short circuit.
Go to step 25.
13 DTC P0122: ATTEMPT TO GENERATE THE OPPOSITE THROTTLE POSITION ANGLE (VOLTAGE) PID READING
NOTE: An intermittent fault can cause a Continuous Memory DTC P0122. If this code is still present after step 13 through step 16, go to step 21.
  • Key OFF.
  • Disconnect TP sensor.
  • Jumper VREF and TP at the TP sensor harness connector.
  • Key ON, Engine OFF (KOEO).
    NOTE: If any NGS communication concerns exists, remove jumper and go to step 16.
  • Access TP V PID with NGS Tester.
  • Is TP V PID greater than 4.60 V? 
 Yes Replace TP sensor.
Go to step 25.
No Remove jumper.
Go to next step.
14 CHECK VREF AND SIG RTN CIRCUITS TO TP SENSOR
  • Key ON, Engine OFF (KOEO).
  • Measure voltage between VREF and SIG RTN at the TP sensor harness connector.
  • Is the voltage between 4.0 and 6.0 V? 
 Yes Go to next step.
No Restore vehicle and refer to TEST 1: VEHICLE REFERENCE VOLTAGE (VREF) , .
15 CHECK FOR OPEN TP CIRCUIT BETWEEN PCM AND TP SENSOR
  • Key OFF.
  • Disconnect PCM.
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance of TP circuit between PCM test pin 89 and TP sensor harness connector.
  • Is resistance less than 5.0 ohms? 
 Yes Go to next step.
No Repair open circuit.
Go to step 25.
16 CHECK TP CIRCUIT FOR SHORTS TO SIG RTN OR PWR GND IN HARNESS
  • Key OFF.
  • Disconnect NGS Tester.
  • Measure resistance between PCM test pin 89 (TP) and PCM test pins 51 and 103 (PWR GND).
  • Measure resistance between PCM test pin 89 (TP) and PCM test pin 91 (SIG RTN).
  • Are both resistances greater than 10K ohms? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to step 25.
No Repair short circuit.
Go to step 25.
17 DTC P1121: TP SENSOR AND MAF SENSOR RATIONALITY CHECK
  • Attempt to start engine.
  • Does engine run? 
 Yes Go to next step.
No Check for major leaks, cracks, and openings between MAF sensor and throttle body. If OK, refer to TEST 16: NO START .
18 CHECK MECHANICAL OPERATION OF TP SENSOR
  • Key ON, Engine OFF (KOEO).
  • Access TP V PID with NGS Tester.
  • Slowly move throttle from closed position to wide open throttle position and observe TP V PID.
  • While opening and closing throttle, is there a change in the TP V PID between 0.49 and 4.65 V? 
 Yes Go to next step.
No Replace TP sensor.
Go to step 25.
19 CHECK TP SENSOR SIGNAL HIGH VERSUS THE ENGINE LOAD WHILE DRIVING VEHICLE
  • Key ON, Engine Running (KOER).
  • Drive vehicle, exercising the throttle and TP sensor while accessing PIDs.
  • Access TP V and LOAD PIDs and record readings.
  • Is TP V PID greater than 2.44 V and LOAD PID reading less than 30%? 
 Yes Check for air leaks between the MAF sensor and the throttle body, including air noise sounds while engine is running.
Repair as necessary.
If OK, replace TP sensor,
Go to step 25.
No Go to next step.
20 CHECK TP SENSOR SIGNAL LOW VERSUS THE ENGINE LOAD WHILE DRIVING VEHICLE
  • Drive vehicle exercising the throttle and TP sensor near higher gears (preferably overdrive) while accessing PIDs.
  • Access TP V and LOAD PIDs and record readings.
  • Is TP V PID reading less than 0.24 V and LOAD PID reading greater than 55%? 
 Yes Check that TP sensor is securely mounted to throttle body. If Continuous Memory P1121 is now present, replace MAF sensor.
Go to step 25.
No Unable to identify fault at this time.
Go to step 25.
21 CHECK FOR TP CIRCUIT INTERMITTENT VOLTAGE INPUT
  • Start engine and bring to idle.
  • Run throttle up to 1500 rpm for 5 seconds.
  • Access TP V PID for a fault indication while performing the following:
    • Lightly tap on TP sensor and wiggle harness connector to simulate road shock.
  • Is TP V PID changing below the minimum 0.49 V or above the maximum 4.65 V? 
 Yes Inspect TP sensor connector.
If OK, replace TP sensor.
Go to step 25.
No Go to next step.
22 CHECK TP SENSOR HARNESS FOR INTERMITTENT OPENS AND SHORTS
  • Access TP V PID.
  • Key ON, Engine OFF (KOEO).
  • Perform the following:
    • Grasp harness closest to the TP sensor connector.
    • Shake and bend a small section of the harness all the way to the dash panel.
    • Wiggle, shake and bend the harness from the dash panel to the PCM.
  • Is TP V PID changing below the minimum 0.49 V or above the maximum 4.65 V? 
 Yes Isolate fault and repair as necessary.
Go to step 25.
No Unable to duplicate or identify fault at this time.
Go to step 25.
23 ATTEMPT TO RE-CREATE DTC OR DRIVEABILITY SYMPTOM
NOTE: If KOER Self Test terminates when placing transmission range selector lever in gear (drive or reverse), go directly to step 24.
  • Attempt to drive vehicle, while still in KOER Self Test.
  • Key OFF, wait for 15 seconds.
  • Start engine again.
  • Activate KOER Self Test.
  • Is DTC P0121 still present or does KOER Self Test again fail to terminate? 
 Yes Go to next step.
No Verify symptom no longer exists.
Go to step 25.
24 CHECK TP OR SIG RTN CIRCUITS FOR OPEN IN HARNESS
  • Disconnect PCM and TP sensor.
  • Install Breakout Box, leave PCM disconnected.
  • Measure resistance of TP circuit between PCM test pin 89 and TP sensor harness connector.
  • Measure resistance of SIG RTN circuit between PCM test pin 91 and TP sensor harness connector.
  • Are both resistances less than 5.0 ohms? 
 Yes Repair open circuit.
Go to step 25.
No Replace TP sensor.
Go to step 25.
25 VERIFY TROUBLESHOOTING OF DTCs COMPLETED
  • Make sure to reconnect all disconnected connectors.
  • Clear DTCs from PCM memory using NGS tester generic OBD-II function.
  • Perform PCM Quick Test.
  • Is same DTC present? 
 Yes Replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Repeat PCM Quick Test.
No If any other DTC is present, go to applicable DTC inspection.
If no DTC is present, troubleshooting complete.
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