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Ford Focus Ink 2003 - Dtc 9318 With New Battery

Eddie Catflap

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Hi all,

New Ford Focus owner here and new forum member.

A couple of weeks ago I bought a 2003 Ford Focus Ink. Sadly the engine management light illuminated after a couple of days of driving. Using the self-diagnostic check in the LCD display showed a DTC code of 9318 (low voltage) had been logged. The battery voltage without the engine running showed as being around 10 volts and 13.5 with the engine running.

I replaced the battery with a new Halfords calcium one (as per their website suggestion for my registration number) and the engine management light was no more. Sadly 100 miles later and the engine management light has illuminated again. The self-diagnostic check shows a DTC code of 9318 and a battery voltage of 11.8 without the engine running and 13.5 with the engine running.

Please could someone help me to further diagnose why the engine management light has illuminated again when the battery and alternator appear to be healthy (to my untrained eye at least)?

Many thanks in advance,


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It will need to go to the dealer and have the alternator smart charge and 3 pin connector checked it should be at 14.4v running so the alternator isnt doing the job possibly the smart charge regulator has gone or theres a break in the 3 pin wiring harness to the smart charge

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exactly as artscot said, i had the issue of the battery light coming on and the alternator and battery giving poor voltage. Turned out a wire had snapped in the wheel arch.

It cost around £120 for dealers to fix.

not many garages know about the smart charge system, thus dealer is better.

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pretty much just wasted lol

dont worry mate, think of how i felt when i bought a new battery from halfrauds and alternator....only for it to turn out it was snapped wire lol

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  • 2 weeks later...

Hi chaps,

Just wanted to post an update on the situation. The car has been with a local Ford garage for a couple of days and the technician advised me that the error code was actually P0420, catalytic converter not operating efficiently (or words to that effect). The car has had a new catalytic converter fitted and the engine management light is no more. The technician also advised me that if the problem really was due to the voltage supply from the battery or alternator then the battery light would have illuminated on the dash, not sure why i didn't realise that!

The moral of the story is not to rely on self-diagnosis from the DTC fault codes provided by the dash, get the error read properly with a fault code reader before guessing what is wrong and splashing out on new parts that don't need to be replaced!

Thanks for everyone's help.

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the technician also didnt say that if its a faulty cell you will get the code but no battery light as well normally its best to get a code reader and clear all the codes then wait a week and see if they return before buying anything free battery tests can be done at most garages

did the technician do a exhaust emission test or just assume that as there was a code it must be the cat its something ive never had to replace yet

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