2000 Mazda B2500 SX, AutomaticFACTORY OEM SERVICE PROCEDURE

Misfire Detection Monitor Disabled

DTC P1309 DETECTION CONDITION AND POSSIBLE CAUSE

DTC P1309 MISFIRE DETECTION MONITOR DISABLED
DETECTION CONDITION 
  • P1309 indicates the misfire detection monitor is disabled, usually due to the input signal generated by the camshaft position sensor (CMP) when sensing the passage of teeth from the CMP wheel.
POSSIBLE CAUSE 
  • Damaged CMP.
  • Damaged PCM.
  • ECT, MAF and CKP sensors
HINT  CMP Sensor Description 
  • Magnetic transducer.
  • Detects the position of the camshaft and identifies when piston No. 1 is on its compression stroke. A signal is then sent to the PCM and used for synchronizing the firing of sequential fuel injectors.
G03988153Courtesy of MAZDA MOTORS CORP.
DTC P1309 INSPECTION

STEP INSPECTION ACTION
1
  • Was PCM Quick Test performed? 
 Yes Go to next step.
No Perform PCM Quick Test.
2 CHECK CMP SENSOR OUTPUT
  • Disconnect PCM.
  • Install Breakout Box and connect PCM.
  • Start engine and vary engine RPM.
  • Measure voltage between PCM test pin 85 (CMP) and PCM test pin 103 (PWR GND).
  • Does the AC voltage vary greater than 0.1 V? 
 Yes Verify the correct installation
See IGNITION SYSTEM .
If CMP is installed properly, replace PCM. See COMPUTERIZED ENGINE CONTROLS .
Go to step 3.
No Replace CMP sensor.
See IGNITION SYSTEM .
Go to step 3.
3 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 Misfire Monitor Drive Cycle.

    See DRIVE CYCLES .

  • Is same DTC present? 
 Yes Replace PCM and repeat PCM Quick Test. See COMPUTERIZED ENGINE CONTROLS .
No If any other DTC is present, go to applicable DTC inspection. If no DTC is present, troubleshooting complete.
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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.