Mazda MX-6 1998, Workshop Manual

Page: 305 / 1282

TROUBLESHOOTING [ENGINE CONTROL KL]
DTC P1121 TP sensor input signal inconsistent with MAF sensor
DESCRIPTION
• Continuous Memory DTC P1121 indicates throttle position is inconsistent with MAF sensor
[Possible Cause]
• Damaged TP sensor • Air leak between MAF sensor and throttle body
• TP sensor not seated properly (almost completely
detached from throttle body)
STEP
INSPECTION ACTION
1 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.
2
CHECK MECHANICAL OPERATION OF TP
SENSOR
• Key on, engine off.
• Access TP V PID with NGS tester.
• Slowly move throttle from closed throttle
position to wide open throttle position and
observe TP V PID for smooth reading
change.
• While opening and closing throttle, is
there sudden drop in TP V PID below
0.66 volts or sudden jump in TP V PID
1.20 volts?
Yes TP sensor has internal substrate problem.
REPLACE TP sensor.
RERUN OBD Test.
No Go to next step.
3
CHECK TP SENSOR SIGNAL HIGH
VERSUS ENGINE LOAD WHILE DRIVING
VEHICLE
• Key on, engine running.
• Do normal drive, exercising throttle and TP
sensor while accessing PIDs.
• Access TP V PID and LOAD PID with NGS
tester and record readings.
• Is TP V PID greater than 2.44 volts and
LOAD PID reading less than 25%?
Yes
CHECK for air leaks between MAF sensor and throttle
body including air noise sounds while engine is running.
SERVICE as necessary,
if okay, REPLACE TP sensor.
RERUN OBD Test.
No Go to next step.
4
CHECK TP SENSOR SIGNAL LOW VERSUS
ENGINE LOAD
• Key on, engine running.
Note
• If vehicle does not Start, go to ENGINE
SYMPTOM TROUBLESHOOTING.
• Access TP V PID and LOAD PID with NGS
tester and record readings.
• Is TP V PID reading less than 0.24 volts
and LOAD PID reading greater than
60%?
Yes
CHECK for TP sensor loosely connected to throttle body
(screws not securely tightened down).
SERVICE as necessary.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
DRIVE vehicle exercising throttle.
RERUN OBD Test.
If Continuous Memory P1121 is now present, REPLACE
MAF sensor.
No Go to next step.
5
CHECK TP SENSOR SIGNAL LOW VERSUS
ENGINE LOAD WHILE DRIVING VEHICLE
• Key on, engine running.
• Do normal drive, exercising throttle and TP
sensor near higher gears (preferably
overdrive) while accessing PIDs.
• Access TP V PID and LOAD PID with NGS
tester and record readings.
• is TP V PID reading less than 0.24 volts
and LOAD PID reading greater than
60%?
Yes
CHECK for TP sensor loosely connected to throttle body
(screws not securely tightened down).
SERVICE as necessary.
RESET PCM to completely clear DTCs.
c r After Repair Procedure
COMPLETE OBD II Drive Mode.
DRIVE vehicle exercising throttle.
RERUN OBD Test.
If Continuous Memory P1121 is now present, REPLACE
MAF sensor.
No
Unable to identify fault at this time. If vehicle is still No
start, Go to ENGINE SYMPTOM TROUBLESHOOTING.
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