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sprinkles08, ASE Certified Technician
Category: Car
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Experience:  ASE Master and Advanced level certified. Factory trained with 17 years dealership experience
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Infiniti Q45: Good evening,I have a 2000 infiniti Q45 with

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Good evening,
I have a 2000 infiniti Q45 with approximately 98,000 mikes. I keep getting diagnostic trouble codes P0325, knock Sensor 1 Circuit (Bank 1) and P0745, Pressure Control Soleniod A.
When I bought the car there were no trouble codes stored in the ECM. About two weeks later, when I attempted to start the car, it cranked slowly before starting and code P0745 first appeared. I decided to have the transmission serviced that weekend and the car stalled and would not resart until I replaced the battery. I replaced the battery and it stalled again after driving for about an hour. The car had to be towed as the new battery was dead. The mechanic indicated that after a period of time diagnosing the problem that the exciter wire was broken. The car had been in a frontal crash before I purchased it. Code P0745 reappeared and is still present. Code P0325 appeared later and is still present. In addition to repairing the exciter wire, I have replaced the dropping resistor relay, had the transmission fluid exchanged, transmission filter replaced and most recently replaced both knock sensors and pigtails. Both trouble codes remain. I have checked related fuses and they are good. I suspect an electrical problem especially since the knock sensor code reappeared after both were replaced. What else do you suggest other than going inside the transmission which shifts perfectly?

Hello and welcome to JustAnswer!


If the knock sensors and harnesses have been replaced yet the code is still setting then the problem could either be in the wiring harness between the knock sensor harness and the ECM, or it could be in the ECM itself. A wiring problem would be much more likely. It could be a connection issue, open circuit, or short to power or ground or another circuit. The next step will be to test the knock sensor wiring, odds are there is a wiring problem.


P0745 is for the line pressure solenoid on the transmission valve body. This code can be caused by a bad solenoid, wiring issue, or the transmission control module. It's not likely to be the transmission control module but the wiring and solenoid should be tested, most solenoid circuit codes are caused by failed solenoids.

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