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Discussion Starter · #1 ·
I recently purchased a salvaged 2017 Q50S and set about bringing it back to life. There was visible damage to the main engine harness (24012-6HE3A) and I have replaced that myself (a lot of work). I am still getting a bunch of codes and the underlying theme is the sensor circuit (bank 1) is either intermittent, low, open, or short-circuited.
Some of the related codes are:
  • P0113 (IAT Circuit High Output)
  • P0235 (Turbocharger Boost Sensor A Circuit Malfunction)
  • P0237 (Turbocharger Boost Sensor A Circuit Low)
  • P2564 (Turbo Boost Control Control Sensor Circuit Low)
  • P2566 (Turbo Boost Control Control Sensor Circuit Intermittent)
I would like to fix this myself and have spent time inspecting the (internal) harness (24011-4HK6B) but not spotting any visible damage
Any pointers, insights, help would be appreciated.
 

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Are you sure your bank 1 MAF sensor is good? Are you getting 5 VDC at the MAF's connector, F99 (terminal 4 to ground) when it's disconnected from the MAF? Have you checked for continuity between the ECM and the MAF? (connector F99, terminal 4 to connector F143, terminal 40)
 

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Discussion Starter · #3 ·
Are you sure your bank 1 MAF sensor is good? Are you getting 5 VDC at the MAF's connector, F99 (terminal 4 to ground) when it's disconnected from the MAF? Have you checked for continuity between the ECM and the MAF? (connector F99, terminal 4 to connector F143, terminal 40)
Thanks for getting back to me. I have done any of the items you raise so I will switch the MAF Sensors around and check what happens. I will get back here with what I observe.
 

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Discussion Starter · #4 ·
Thanks for getting back to me. I have done any of the items you raise so I will switch the MAF Sensors around and check what happens. I will get back here with what I observe.
@Avedis53 ...I swapped the MAF sensors and did not get a code for bank 2. I am not registering the 5VDC at the MAF's connector for bank 1.
I opened ECM but I do not know which of the three connectors and pin combination I need to connect/test for continuity. Any help/insights appreciated.
 

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Wow! Another one. I had no idea rebuilding salvaged Q50s was a such a common thing!
Best of luck to you. Sincerely. Myself, I would pick a different hobby.
 

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There are 3 connectors for the ECM. Two of them (F142 and F143) are identical connectors and I'm not sure which one is F143. The third connector is smaller and not part of this test. F143 is the one you want to check for continuity to F99 (bank 1 MAF). The pinout locations on F143 and F142 are different though.

Here's the pinout diagram for F143:

92466



Here is F142, notice the difference in the pinouts:

92467



Check for continuity between pin #40 on F143 and pin #4 on F99 (MAF sensor bank 1).
 

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Discussion Starter · #8 ·
There are 3 connectors for the ECM. Two of them (F142 and F143) are identical connectors and I'm not sure which one is F143. The third connector is smaller and not part of this test. F143 is the one you want to check for continuity to F99 (bank 1 MAF). The pinout locations on F143 and F142 are different though.

Here's the pinout diagram for F143:

View attachment 92466


Here is F142, notice the difference in the pinouts:

View attachment 92467


Check for continuity between pin #40 on F143 and pin #4 on F99 (MAF sensor bank 1).
Thanks @Avedis53 .....this is just what I was looking for. I will go test for the connectivity and share what I discover. You are a star!
 

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Discussion Starter · #9 ·
There are 3 connectors for the ECM. Two of them (F142 and F143) are identical connectors and I'm not sure which one is F143. The third connector is smaller and not part of this test. F143 is the one you want to check for continuity to F99 (bank 1 MAF). The pinout locations on F143 and F142 are different though.

Here's the pinout diagram for F143:

View attachment 92466


Here is F142, notice the difference in the pinouts:

View attachment 92467


Check for continuity between pin #40 on F143 and pin #4 on F99 (MAF sensor bank 1).
@Avedis53 there was no connection/flow between the ECM (F143/40) and MAF (F99/4). Anything else I can do?
 

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Well, assuming I read the pinouts correctly and the wiring diagram applies to your car, then the next step is to pray.

Seriously, you've checked the voltage to the F99 connector and there is none and when you ring out the harness between the ECM and MAF1 there is infinite resistance. All I can offer is to start tracing the harness from the ECM to the MAF, looking for damage. I hope I'm not overlooking anything simple here and sending you down a rabbit hole. Good luck.
 

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Discussion Starter · #11 ·
Well, assuming I read the pinouts correctly and the wiring diagram applies to your car, then the next step is to pray.

Seriously, you've checked the voltage to the F99 connector and there is none and when you ring out the harness between the ECM and MAF1 there is infinite resistance. All I can offer is to start tracing the harness from the ECM to the MAF, looking for damage. I hope I'm not overlooking anything simple here and sending you down a rabbit hole. Good luck.
@Avedis53 ....I checked all the pins on the F99 connector just to be sure. I will start tracing the harness from the ECM to the MAF. If all else fails I will try and replace the entire harness. I truly appreciate your help.
 

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Discussion Starter · #12 ·
@Avedis53 ....I ended up buying the harness and replacing it myself - a fun challenge which included dismantling the whole front end of the car to gain access to the last connector next to the AC compressor.
Now the engine turns over but the car does not start!
I am going over all the connectors to make sure I left nothing unclipped but I am wondering if there is/are particular one/ones I should look out for.
I did notice a couple of times that there was a No Key detected warning whilst trying to get the car started, will that be a reason why the car would not fire up?

Many thanks.
 

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@Avedis53 ....I ended up buying the harness and replacing it myself - a fun challenge which included dismantling the whole front end of the car to gain access to the last connector next to the AC compressor.
Now the engine turns over but the car does not start!
I am going over all the connectors to make sure I left nothing unclipped but I am wondering if there is/are particular one/ones I should look out for.
I did notice a couple of times that there was a No Key detected warning whilst trying to get the car started, will that be a reason why the car would not fire up?

Many thanks.
I couldn't begin to tell you where to look if you replaced the harness. I would think your car wouldn't even turn over if it were a key problem. Battery good in the fob? The BCM activates the inside key antennas and checks if the fob is in the vehicle. If no fob is detected then you get the No Key warning on the display. Are you still able to turn the engine over after the warning?

We have a couple of Infiniti techs as members now. Hopefully they will stop by here and help you out.
 

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Discussion Starter · #14 ·
I couldn't begin to tell you where to look if you replaced the harness. I would think your car wouldn't even turn over if it were a key problem. Battery good in the fob? The BCM activates the inside key antennas and checks if the fob is in the vehicle. If no fob is detected then you get the No Key warning on the display. Are you still able to turn the engine over after the warning?

We have a couple of Infiniti techs as members now. Hopefully they will stop by here and help you out.
@Avedis53 ...the engine turns over when when I have seen the warning. The battery is good in the fob. It reminds me of pulling out the spark plugs/pulling out the fuel pump fuse and starting the engine. I will check all the connectors over the coming week but any insights very much appreciated. Thanks for the quick response.
 

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All I can say is double check all your connectors.
 

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You must have double checked your connectors then? Which connectors were swapped?
 

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Discussion Starter · #18 ·
@Avedis53 ...yes, found the cam sensor connectors on the right bank plugged into the wrong sensor, exhaust into intake and intake into exhaust. Swapped the connections and the vehicle now starts and runs.
 

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Well done then!
 
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