# No Communcation Code



## Danaleer (Feb 10, 2014)

1998 Maxima... this car has been nothing but problems due to previous owner's neglect (and my parents not checking it out before they bought it as a surprise for me). 

I have inspection soon and my car has been running really rough. Need to change coil pack. But to figure out which one, we need a misfire in cylinder ? code, and when my friend ran the reader, it only came up with no communication. He mentioned my cig lighter fuse might be blown, but I can still use a car charger.

Any way to figure out what could be causing the code???


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## smj999smj (Jan 1, 2006)

Sometimes a bad coil pack will send out RF interference through the engine control harness and interrupt the communication to the ECM. You could pull all of the coil packs and check for cracks in the body of the coils and replace any that are cracked. If all of the coils are original or appear so, I would recommend replacing the entire set. It's expensive, but coil packs have been problematic on these models and if one's bad, the others are probably not far behind. Also, check for oil in the spark plug wells and make sure the proper type NGK spark plugs are installed and in good condition. If you still have a no communication issue, you could have a bad ECM, but in order to determine that, one would have to follow the factory service manual procedure for the symptom. "No communication with ECM" in the EC section.


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## Danaleer (Feb 10, 2014)

Went to Pepboys & and they read the scan... I actually got some codes!

PO300 - Multiple Misfire
PO139 - B1 Sensor Oxygen Sensor Circuit Slow Response
PO138 - O2 Sensor B152 High Voltage


Still thinking it could be coil packs? Or something else causing all these?


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## smj999smj (Jan 1, 2006)

P0138 & P0139 are both malfunction codes for the Bank 1, downstream oxygen sensor. This sensor is a monitoring sensor and has know affect on drivability. That said, the codes could be a result of the misfire, which if so, would lead me to concentrate on Bank 1 for the misfiring cylinder(s). Bank 1 is the right bank, or in the case of the Maxima, the bank closest to the firewall. If you can't find any physical evidence on the coils or oil leaks into that bank's spark plug wells, you might consider replacing the three coil packs on that particular bank, erase the stored codes, and see what happens. If the misfire does not re-occur but the O2 sensor returns, then I would replace the Bank 1 rear O2 sensor.


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## Danaleer (Feb 10, 2014)

I checked w my mechanic and he'll do the labor for me, and the sensor is only 30 so I'm going to go ahead with it anyway just because one of the symptoms of a bad sensor is high fuel consumption, and my car DOES eat gas like candy. And when he ran his reader, it still wouldn't give him a code so he wants to wait for a better one for the misfire code. I do think its a bad coil pack, only because when I changed the one before, the car did run smooth afterwards.


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## Danaleer (Feb 10, 2014)

And did you mean NO affect on on driveability or know? I was confused


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## smj999smj (Jan 1, 2006)

Front, or upstream oxygen sensors are used by the ECM to help it determine the fuel management. Rear, or downstream oxygen sensors are used only by the ECM to determine if the catalytic converter is working efficiently. Replacing the rear oxygen sensor will not have any affect on your Maxima's fuel consumption nor the way the engine runs.


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## Danaleer (Feb 10, 2014)

"For fuel management purposes, your engine’s ECU would use the input from the bank 1 O2 sensor to readjust the fuel mixture as needed for optimum emissions, fuel economy and performance."

The rear sensor I'm changing is in bank 1, wouldn't that help any?


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