W204 Limp Mode - Wheel Sensor?
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C300
W204 Limp Mode - Wheel Sensor?
Hey Folks,
Looking for some advice. My son bought a new 2010 C300 and babied it for 10 years and was looking for a new car and I told him I would buy the MB since I know how well it’s been taken care of. Always had the recommended service and has 142,000 kms on it. There is one issue now that I’m hoping someone can shed some light on because while I used to be a mechanic many years ago I don’t know much about the later models. He’s also in a different province than I so I don’t have access to the car just yet with the COVID restrictions.
About a month ago his ABS light came on but the car was running fine and he didn’t get around to getting it looked at. Then, earlier this week it went into limp mode (2nd gear only) ironically on the same day he picked up his new Honda. He dropped it to a garage ( not the MB dealer) and they checked it out and said bring it to the dealer because it need the transmission valve body torn apart. The codes that showed up are P0720, P0721 and U140C. The tranny code is obviously speed sensor related but if I’m reading right, it means different readings from vehicle speed and transmission speed. Now they have confirmed that the right rear wheel speed sensor is bad so my first thought is the faulty speed sensor could set those codes but the ABS light was on for a month so that’s’ got me wondering.
So can anyone here weigh in and tell me if the wheel sensor could throw those codes and put it in limp ode or am I definitely looking at conductor plate/valve body?
Thanks all
Looking for some advice. My son bought a new 2010 C300 and babied it for 10 years and was looking for a new car and I told him I would buy the MB since I know how well it’s been taken care of. Always had the recommended service and has 142,000 kms on it. There is one issue now that I’m hoping someone can shed some light on because while I used to be a mechanic many years ago I don’t know much about the later models. He’s also in a different province than I so I don’t have access to the car just yet with the COVID restrictions.
About a month ago his ABS light came on but the car was running fine and he didn’t get around to getting it looked at. Then, earlier this week it went into limp mode (2nd gear only) ironically on the same day he picked up his new Honda. He dropped it to a garage ( not the MB dealer) and they checked it out and said bring it to the dealer because it need the transmission valve body torn apart. The codes that showed up are P0720, P0721 and U140C. The tranny code is obviously speed sensor related but if I’m reading right, it means different readings from vehicle speed and transmission speed. Now they have confirmed that the right rear wheel speed sensor is bad so my first thought is the faulty speed sensor could set those codes but the ABS light was on for a month so that’s’ got me wondering.
So can anyone here weigh in and tell me if the wheel sensor could throw those codes and put it in limp ode or am I definitely looking at conductor plate/valve body?
Thanks all
Member
Joined: Dec 2017
Posts: 230
Likes: 38
From: NYC
2008 S550 4Matic, 2007 GL450, 2008 C300, 2018 GLE63 AMG
Transmission should still shift is the wheel speed sensor is defective, the 7g transmission has its own speed sensor inside, if thats defective the the transmission will be stuck in limp mode... you need the have a proper scanner to check the modules individually, worse case scenario you need a new/replacement valvebody, you don necessarily to goto the dealer to do it but does need special equipment to program, limitation is based on your area..
