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I have a check engine light on and I put the computer on it and one of the codes is P1309… what is p1309… I have a 2000 ford ranger

P1309 Misfire monitor AICE chip fault

And sorry, but that’s all I’ve got for you. I do ok with a lot of trouble codes, but don’t know where to start with that one. (I do fear anything that says “chip fault” though).

I’m sure someone else can tell you how you might sort it out. It will help if you add info about the truck - mileage, what problems is it having, some idea of maintenance history, etc.

Diagnostic Trouble Code (DTC) P1309 indicates Misfire Detection Monitor is not enabled.

Google it. Wiki will tell you how to do the witch hunt.

p1309 is a CMP (cam postion sensor) fault code.

Code P1309 relates to a problem with the camshaft position sensor circuit.


I thought these codes were standardized…Do these codes have random meanings assigned to them at the whim of the manufacturer? Do they vary between models of the same vehicle?? “Oh, lets see, what does P1309 mean today…”

When there’s P0xxx codes, those are the generic codes mandated by the EPA. When there’s a P1xxx code, that’s a manufacturer specific/enhanced code. That’s one of the reasons why you want a code reader/scanner that can read these manufacterer specific/enhanced codes.


Going from memory because it would take me an hour to confirm it, codes below 0999 are predetermined and are emission related. Codes above P0999 are used by manufacturers for conditions/devices that aren’t in the predetermined list. They aren’t all that common, and the couple I’ve seen were constructed by prefixing a 1 to a predetermined code that is vaguely related to the problem. In this case P0309 is documented as Cylinder 9(!!!) misfire so P1309 probably relates to a misfire related problem or to using the misfire detection hardware to doing something else (or to some other problem with cylinder 9 – which your Ranger doesn’t have one of)

The definition of P1309 is: Misfire monitor hardware - CMP misaligned, CKP/CMP noise, PCM AICE chip. Expanded definition: "There is a problem with the hardware (wires, sensors, engine computer) which is involved in detecting misfire. The hardware problem could be a misaligned CMP (CaMshaft Position sensor), or CKP (CranKshaft Position sensor) or CMP sensor noise (“static”), or a chip inside the engine computer." Connect backprobes of digital electrical multimeter (“voltmeter”) to engine computer (PCM) pins 58 and 103. Idle engine and watch the voltage signal from the CMP vary from 2 to 8 volts. Check the CMP wires, from the CMP to the engine computer for shield (wire foil covering) for ground. The shield should be grounded. Where the wires connect to the CMP, spray a cleaner in that area to blast away oil and gunk. Disconnect the connector at the CMP and check the connector for damage, gunk, and that rubber piece that should be around the pins.
If someone has had the CMP out, they may have put it back in incorrectly (out of “synchronisation”). You’ll need the repair manual, and the tool for setting the camshaft position sensor (the synchronizor). A new synchronisor comes with the tool, or you can borrow it, or get it from ebay (about $35). The CMP shaft may be worn, which could cause an irregular voltage signal.
Replacing the camshaft position sensor, using the synhronisor tool to correctly align it, may be your fix.

I found a great reply in another forum about this code. This is for a Ford specific code.

The code means that there’s too much variance in the speed of the firing of the cylinders and therefore the misfire monitor is disabled, in a nut shell
the pcm is saying the car is running too rough to pinpoint exactly which cylinder is misfiring. This can be caused by problems with
cam sensor or circuit
crank position sensor or circuit
maf sensor or circuit
coolant temp sensor or circuit

If you have one cylinder that’s missing really bad then you can generate this code. Assuming that the 2 sensors you changed are working as they should then you might have to looka t doing a cylinder balalnce test, compression test etc to determine if you have any weak cylinders and then go from there, how does the car run?

Hope this helps.

And, the other codes are what?