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Discussion Starter #1
I had replace my speed sensor on my q50 2014 and the same code keep popping the mechanic said I need a new transmission help please
 

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Did you replace a ABS speed sensor when the code required a transmission output speed sensor? Cause would be odd if u replaced the correct sensor and code still comes back after new part.
 

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I had replace my speed sensor on my q50 2014 and the same code keep popping the mechanic said I need a new transmission help please
If the mechanic is thinking a new transmission, then it isn't a wheel speed sensor. He's thinking there is a problem with one of the two input speed sensors or the output speed sensor that are part of the transmission. It would be helpful if you know the DTC that was thrown to post it here. The speed sensors can be replaced. It could also be the control valve and TCM that needs replacement.

A new transmission??? If the mechanic is thinking that then we aren't getting the whole story.
 
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The transmission speed sensor he replaced it and same code pop up, i want to know if anybody had a similar problem before i spend money the codes P0720 P0500
 

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P0720 - Output Speed Sensor Circuit

DTC detection condition

• The vehicle speed detected by the output speed sensor is 5 km/h (3 MPH) or less when the vehicle speed transmitted from the combination meter to TCM is 20 km/h (12 MPH) or more. (Only when starts after the ignition switch is turned ON.)

• The vehicle speed transmitted from the combination meter to TCM does not decrease despite the 36 km/h (23 MPH) or more of deceleration in vehicle speed detected by the output speed sensor. when the vehicle speed detected by the output speed sensor is 36 km/h (23 MPH) or more and the vehicle speed transmitted from the combination meter to TCM is 24 km/h (15 MPH)
or more.

So basically, the output speed sensor is seeing a different vehicle speed than the combination meter's speedometer. This is caused by a bad harness or connector in the wiring circuit or the output speed sensor is bad. This causes the TCM to go into Fail-Safe mode which will limit the shifting to the lower 3 gears and manual shift mode is prohibited.


P0500 - Vehicle Speed Sensor A

DTC detecting condition

At 20 km/h (13 MPH), ECM detects the following status continuously for 5 seconds or more: The difference between a vehicle speed calculated by a
output speed sensor transmitted from TCM to ECM via CAN communication and the vehicle speed indicated on the combination meter exceeds 15km/h (10 MPH).


Again, there is a discrepancy between the transmission's output speed sensor and the combination meter's speedometer. This can be caused by a harness or connector that is open or shorted, the combination meter is faulty, the ABS actuator and electric control unit is faulty, a faulty wheel speed sensor, a faulty TCM or a faulty output speed sensor.

I'm not sure why the mechanic would think that the transmission would need replacement since these DTCs are pointing at other replaceable components, most likely the output speed sensor or perhaps a wheel speed sensor. Since the speed sensor (assuming it was the output speed sensor) was replaced, it could be a wiring problem or one of the other causes listed. You might consider having another dealership look at the problem if you have a choice.
 

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I have a similar problem with only P0500 Vehicle Speed Sensor "A". No other codes, no ABS faults, 3 warnings repeating on display, which trigger after reaching a dozen MPH. Many idiots lit. No drivability issues but cruise is disabled as as are all the other safety functions. Where should I look for wiring/connections/sensors that might cause this?
 

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BTW, taking into dealer next week to diagnose, $120 flat fee. Hoping their diagnosis tools are worth it.
 

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Without listing some DTCs from an OBDII scanner, it's hard to say what all is going on. Good luck!
 

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My scanner is a cheapo but that was my first step, "...a similar problem with only P0500 Vehicle Speed Sensor "A". ".
 

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Hopping on this thread, looking for tips, as I have many of the same idiot lights. 2016 Q50 RS 400. Had a P0500 that stayed cleared for about 200 miles so far, but getting simultaneous additional codes of:

C1105 - ABS RR RH SENSOR2
C1B92 - BRAKE CONTROL SYSTEM
C1A50 - ADAS MALFUNCTION
C1A16 - RADAR STAIN/BLOCKED

These codes trigger the lights shown.

It appears that C1105 and C1B92 are probably related (ABS), and C1A50 and C1A16 are probably related (ADAS), but I don't know enough about these systems to do further troubleshooting, or see something that is in common between all four (other than "all of your electrical control units are fried and need to be replaced").


 

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C1105 - malfunction of rear, right-hand wheel sensor.

C1B92 - malfunction is detected in the ABS actuator and electric control unit system.

C1A50 - ADAS control unit malfunctioning.

C1A16 - ICC sensor area of the front bumper is being affected by foreign materials adhering to it.

I'd suspect the RRH wheel speed sensor needs to be replaced as that has been reported here multiple times. I'd check it out and replace it first and see if any of the other DTCs clear.

The other DTCs could get spendy if you need to replace the ADAS control unit, ABS actuator and electric control unit and/or ICC radar sensor.

Is the area in front of the ICC radar sensor clean?
 

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Thanks for the feedback! I'm pretty new to working on this car. It's the first of 4 Infinitis where I let the factory warranty lapse before selling the car or extending.

Is the area in front of the ICC radar sensor clean?
I'm going to be an idiot on this one. I know there are at least 5 different types of sensors in the front - the one below the rearview mirror (I think this is for headlight auto-dim/bright), the one set back above the rearview, the front facing camera, the one close to the ground below the passenger headlight behind a panel, and the four round sensors in the bumper. I don't know which one is ICC radar.

I had just cleared all of the extended DTCs, and all four of these came up at once on a single drive cycle.

Interestingly I did examine the rear-right wheel sensor. I just recently had the differential seals replaced at the dealer, under powertrain warranty. I did not realize how close these sensors are to that area, so I'm wondering if something happened during that dealer repair.

The RR sensor looks weirdly aligned (see image), like not completely aligned with the index grooves, and there appear to be some light tool marks on the index grooves. I'm not sure if either of these would affect the sensor. The RL sensor seems fully aligned over the index grooves, but there does not appear to be any way to adjust the alignment as the sensor is set into a hole, unless the axle with the index grooves itself is out of alignment.

I pulled the sensor and found it to be greasy and dirty - probably from differential leaks. I cleaned it and reinstall, but I don't know that it did any good, because I believe the sensor is magnetic. It is fairly exposed, so I imagine dirt and grease don't affect normal operation.


 
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