Q: 2008 Mazda 5 has codes P0661 and P0720

asked by on January 31, 2017

I've engine fault lights up, so I went to nearby workshop to check. He used a wireless device to test and the error code is P0661. He cleared the error and I ask me to come back if error comes out again. The next day the engine fault lights up again and then goes off the next day. I ignore and continue to drive for a week. Then suddenly while on the highway, the engine fault and AT lights up, the car jerk a little then AT light goes off. But the engine fault remains on. I went to another mechanic, this time the computer they use is wired type. The error fault they found now is OSS, and I couldn't remember the code. It could be be P0720 or P0721 etc. He replaced the speed sensor. I thought the issue solved but two days later the car jerk at the highway again. The AT lights up followed by engine fault lights up. The AT light then goes off. These light keeps going on and then off again the next day or day after. What do you think the root cause can be? Could it be the Gearbox spoil?

My car has 130000 miles.
My car has an automatic transmission.

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Input from the vehicle speed sensor (VSS) is used by the transmission control module (TCM) to calculate shift points, torque converter operation and other transmission functions. Code P0720 stands for Vehicle Speed Sensor circuit malfunction. Typically, this code indicates a problem with the VSS circuit and not an internal transmission problem. If the problem continues even after sensor replacement, the issue is either the circuit wiring or the transmission control module. Code P0661 stands for Variable Intake Air System Solenoid Circuit Low Input and is not likely to be related. I recommend getting a second professional opinion on the issue, sine the initial shop was not able to fix the problem. YourMechanic is an excellent option for your check engine light diagnosis because we come to your home or office.

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