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CEL HELP Finally got my check engine light fixed... unfortunately its on :/

KevinSonOfDad

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Ford Technician
ASE Certified Tech
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Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
Figured before i dig super deep i may as well list the codes i have and see if any of yall have had similar problems and what your fixes were (also to help people in the future with similar problems rather than just googling it on my own)

KOEO (Key On Engine Off):
121 Indicates Throttle position voltage is inconsistent with MAF (where applicable)

KOER (Key On Engine Running):
412 Unable to control RPM during low RPM self test
116 Coolant Temperature Sensor out of self test range
121 Indicates Throttle position voltage is inconsistent with MAF (where applicable)
411 Unable to control RPM during high RPM self test
129 Insufficient manifold absolute pressure/mass air flow change during dynamic response check
167 Insufficient throttle position sensor change during dynamic response check

(all codes were obtained via jumping the self test port and counting CEL flashes. All descriptions were obtained via my haynes manual)
 


RonD

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Clean MAF sensor easy to do, 121
Clean IAC Valve, not hard to do, 411 and 412

116 coolant temp, was engine fully warned up, about 1/2 on temp gauge, if not then ignore code for now

ignore 129 and 167 its was for "Goose" test, which means you needed to press gas pedal down 1/2 way at a certain time and then release it, in the engine running test

121 part 2, Test voltage at TPS(throttle sensor), key on engine off
test while its 3 wire are hooked up
top wire 5volts
center wire .69-.99 volts, under 1 volt

Open throttle slowly and center wire voltage should go up, at wide open it should be 4.5volts
Should be smooth voltage no jumps or drops

BEFORE doing an repairs do this:
Clear codes by unplugging the jumper wire while codes are being flashed by CEL
Turn off key
Start engine without jumper in place, idle for 2 minutes REV it a few times, or go for a drive
Turn key off and reinstall jumper
Turn key on, DO NOT start engine
Wait for codes to be flashed, and see which ones are still there
 

KevinSonOfDad

Member
Ford Technician
ASE Certified Tech
Joined
Jul 24, 2022
Messages
44
Reaction score
30
Points
18
Location
Utah
Vehicle Year
1994
Make / Model
Mazda B4000
Engine Type
4.0 V6
Engine Size
4.0 OHV V6
Transmission
Manual
2WD / 4WD
4WD
did the last part already i already kinda ignored the goose test cause i didnt give it enough throttle. not sure if it was warmed up. i did just clean my maf prior to this tho... as well as the IAC but i didnt clean the IAC as good. I will take a look at both as well as testing the tps. Thanks for the timely response
 

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