Abs/traction/brake lights on? C0040 and C0550 codes?

2003 HUMMER H2
172,000 MILES • 4WD • AUTOMATIC
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BHAMDOC1
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Codes are these 2 attched. Do you believe it's usually a bad sensor?
Jul 8, 2026 at 5:15 PM
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BHAMDOC1
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Someone told me the c0050 could be due to low battery voltage. I actually had to jump it everytime but then found that both cables were loose. So i trickle charged the battery and tightened them and now the car starts fine. Someone else told me the big tires could trigger these. Am mot sure if these oem or not or if this is true
Jul 8, 2026 at 5:42 PM
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BHAMDOC1
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also noticed the ground post large bolt that connects the cable to the battery keeps turning, I cannot tighten it more because it goes loose, then I tighten it to a limit, not like the positive post. Have you seen that before and is it usually a bolt or a battery thread issue?
Jul 8, 2026 at 7:32 PM
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BHAMDOC1
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If intighten it without the canle it tightens fine
Jul 9, 2026 at 12:34 AM
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STRAILER
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Sorry, we only handle one problem per thread please start anew question for the battery post issue.

C0040 is associated with the right-front wheel speed sensor circuit.
C0550 generally indicates an internal EBCM/ABS control module malfunction.

I would check the bearing hub which holds the sensor and can cause both problems. IF the hub and sensor are okay I would replace the ABS control module. Check out the images (below). Let me know how it goes
Jul 9, 2026 at 4:16 PM
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BHAMDOC1
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Sorry for the many videos, but looks like the bearing is first to go, and maybe both fronts actually, I attached the new sensor and just left it hanging and started the car but the codes won't delete. so could be that the abs unit is also bad. I cannot tell from the picture where it is located. Are these steering dampers that important say if they are the ones leaking?
Jul 11, 2026 at 12:55 AM
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STRAILER
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Thanks for the videos they helped, yep, those bearing hubs are bad so you need to replace them and that should take care of the ABS lights. They will not clear while the bearing hubs are bad. The second the vehicle rolls the errors return. Next, start a new posts for the steering issue and the shock issue. Here is a video to help you change out the bearing hub.

https://www.youtube.com/watch?v=ZgiPRG6jffc

Please go over this video and get back to me.
Jul 11, 2026 at 2:45 PM
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