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Drew, Super Mazda Tech.
Category: Mazda
Satisfied Customers: 2188
Experience:  19 yrs. experience. Mazda Senior Certified Tech, with Ford, Linc. & Merc. experience. ASE L1 Advanced Certified Master Tech.
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Mazda 6 I have a 04 Mazda 6 That has the following codes u0073,

Customer Question

I have a 04 Mazda 6 That has the following codes u0073, u2516,c1119 and p0303 and p0304. Can anybody shed some light on the situation?
Submitted: 6 years ago.
Category: Mazda
Expert:  Drew replied 6 years ago.

Welcome to Just Answer. My name is XXXXX XXXXX I will be glad to assist you.


Does your car have a misfire and running rough condition??

Customer: replied 6 years ago.

not all the time, it comes and goes.


Expert:  Drew replied 6 years ago.

Disconnect the battery and touch the cable ends together for 30sec. This will reset the module.


With the engine running wiggle the wiring harness from the engine and ignition coil areas to the PCM. Note any running change.


Let me know if you can duplicate the concern.


Also check to see if check engine light comes back on and what the fault codes are.

Customer: replied 6 years ago.

I already did the good ole Ford wiggle test. Testing individual modules I get the communication code faults from the instrument cluster. Is this a common problem or a possible problem. The car has about 100k on it now. someone else has been all over it already

Expert:  Drew replied 6 years ago.

Code P0304 and P0303 are for the rear cylinders. Inspect the injector connectors for broken loose connections also.

Customer: replied 6 years ago.
Check your info because cylinders 1, 2 & 3 are on the back closest to the firewall 4,5, & 6 are closest to the radiator. Per All-dat and Mitchell. By the way I am also ASE Master and L-1 certified.
Expert:  Drew replied 6 years ago.

Yes you are correct.


Now back to the question at hand. I would suspect that you checked the wiring harness connectors and they checked out ok.


1.When you swapped the coils to a different location, did the misfire code change??


2.Do you have a scan tool that can monitor misfire data??


3.After you disconnected the battery and reset the module, which codes came back??


4.Did the U-XXXX codes come back??


Most U-codes are generated because of low battery voltage or module communication software error. If you cleared the U-codes and the didn't come back, don't worry about them. Since a U-code will not cause a misfire concern, lets focus on the misfire codes.


5.Inspect the crankshaft and camshaft position sensors?


6. Check the MAF sensor and the air intake hose between the intake and air cleaner for cracks/torn.


7. Can you watch fuel trims on your scan tool and record the readings during misfire??


Please let me know the answers to all 7 of my questions.


Thanks Drew.