P0073 Bizarre issue
Thread Starter
Newbie
Joined: Sep 2019
Posts: 5
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C300
P0073 Bizarre issue
Hello Everyone, I have surfed this forum on the regular to find DIY fixes for my W204 but this time I hit a brick wall. I know there is plenty of other P0073 threads out there but I found nothing with my symptoms. This morning my outside temp. stopped working with it came the following issues:
CEL (P0073)
Outside temp is offline
Radiator fan is running on full blast all the time
High beam icon is always illuminated on the dash, however the low beams are on and in-fact the high beams do not stay on.
Parking brake light is always illuminated regardless of the actual status of the brakes.
Blinkers work but do not illuminate on the dash.
A/C stopped blowing cold air.
Alarm went silent. Doors lock and unlock but no panic and no beep beep.
the front end of the car does not communicate with the back end of the car
no in cabin lights
These symptoms would come and go. Every-time the outside temp went offline the symptoms would arise; once the outside temp kick back online everything works just fine.
I replaced the ambient air temperature sensor hoping that it would fix the problem, and it did for 5 min. Then, it stopped working again. Tested the battery and it was good, also the wiring going to the sensor looks fine. Does anyone know what the next step might be?
UPDATE: I got the alternator tested and the shop said that it was bad. specifically the voltage regulator. did anyone has similar trouble due to a bad alternator, and do yall know if there is a DIY guide out there.
any input is appreciated. Thank you!
CEL (P0073)
Outside temp is offline
Radiator fan is running on full blast all the time
High beam icon is always illuminated on the dash, however the low beams are on and in-fact the high beams do not stay on.
Parking brake light is always illuminated regardless of the actual status of the brakes.
Blinkers work but do not illuminate on the dash.
A/C stopped blowing cold air.
Alarm went silent. Doors lock and unlock but no panic and no beep beep.
the front end of the car does not communicate with the back end of the car
no in cabin lights
These symptoms would come and go. Every-time the outside temp went offline the symptoms would arise; once the outside temp kick back online everything works just fine.
I replaced the ambient air temperature sensor hoping that it would fix the problem, and it did for 5 min. Then, it stopped working again. Tested the battery and it was good, also the wiring going to the sensor looks fine. Does anyone know what the next step might be?
UPDATE: I got the alternator tested and the shop said that it was bad. specifically the voltage regulator. did anyone has similar trouble due to a bad alternator, and do yall know if there is a DIY guide out there.
any input is appreciated. Thank you!
Last edited by BenzForce1; Oct 9, 2019 at 07:40 AM. Reason: Updates
MBworld Guru
Joined: Dec 2009
Posts: 10,782
Likes: 1,011
NO LONGER ACTIVE
The electronics on this car are very sensitive to voltage spikes and fluctuations. Many of the components you had that were not working properly are controlled by the front SAM, which is a computer that electronically controls various components. It is especially susceptible to voltage irregularities. Whenever you have odd problems like this, checking the operating voltage is the first thing to do. You should see 12.5v - 12.6v at rest, no less than 11v while cranking, and 14v at idle.
Newbie
Joined: Oct 2019
Posts: 6
Likes: 0
C300 w(204)
Hello Everyone, I have surfed this forum on the regular to find DIY fixes for my W204 but this time I hit a brick wall. I know there is plenty of other P0073 threads out there but I found nothing with my symptoms. This morning my outside temp. stopped working with it came the following issues:
CEL (P0073)
Outside temp is offline
Radiator fan is running on full blast all the time
High beam icon is always illuminated on the dash, however the low beams are on and in-fact the high beams do not stay on.
Parking brake light is always illuminated regardless of the actual status of the brakes.
Blinkers work but do not illuminate on the dash.
A/C stopped blowing cold air.
Alarm went silent. Doors lock and unlock but no panic and no beep beep.
These symptoms would come and go. Every-time the outside temp went offline the symptoms would arise; once the outside temp kick back online everything works just fine.
I replaced the ambient air temperature sensor hoping that it would fix the problem, and it did for 5 min. Then, it stopped working again. Tested the battery and it was good, also the wiring going to the sensor looks fine. Does anyone know what the next step might be?
UPDATE: I got the alternator tested and the shop said that it was bad. specifically the voltage regulator. did anyone has similar trouble due to a bad alternator, and do yall know if there is a DIY guide out there.
any input is appreciated. Thank you!
CEL (P0073)
Outside temp is offline
Radiator fan is running on full blast all the time
High beam icon is always illuminated on the dash, however the low beams are on and in-fact the high beams do not stay on.
Parking brake light is always illuminated regardless of the actual status of the brakes.
Blinkers work but do not illuminate on the dash.
A/C stopped blowing cold air.
Alarm went silent. Doors lock and unlock but no panic and no beep beep.
These symptoms would come and go. Every-time the outside temp went offline the symptoms would arise; once the outside temp kick back online everything works just fine.
I replaced the ambient air temperature sensor hoping that it would fix the problem, and it did for 5 min. Then, it stopped working again. Tested the battery and it was good, also the wiring going to the sensor looks fine. Does anyone know what the next step might be?
UPDATE: I got the alternator tested and the shop said that it was bad. specifically the voltage regulator. did anyone has similar trouble due to a bad alternator, and do yall know if there is a DIY guide out there.
any input is appreciated. Thank you!
is there any new news with your car ?
have you tried what I did?
also nowadays In the morning the car goes back to normal and after an hour of driving it goes back to the same problems.
I could not find my ambient temperature sensor in its location. Maybe because the previous owner changed its location.
Thread Starter
Newbie
Joined: Sep 2019
Posts: 5
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C300
I have yet to mess with the modules underneath the seat because I lack the scanner needed to diag them. However I did change the alternator hoping it was a voltage issue but of course that fixed absolutely nothing. I am trying to get the car in the shop within the next couple weeks to get it diagnosed. Ill post back here if I have any new development
Thread Starter
Newbie
Joined: Sep 2019
Posts: 5
Likes: 0
C300
So I woke up today and the issues seems to have fixed it self. I am not sure if its completely gone because I have yet to drive the vehicle. Also, its a cold and very humid day so I am not sure if that has to do with anything working properly. However the car is showing P0410 as a pending code. Ill update as I drive it work today.
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