Fault phenomenon: a 2003 Peugeot 607, using 6 cylinder 3.0L engine and 4HP-20 automatic transmission. After completing the two level maintenance, the fuel door does not rise 4 gears. Failure reason: test car found that the car 2, 3 gear normal, 3 gear engine speed less than 2000r/min can rise 4 gear, if more than 2000r/min, even the loose valve will not enter the 4 gear, and enter the 4 gear after the normal refueling. The engine system and ABS system are all normal with the tester, while the transmission system has TCC torque converter locking clutch slip fault code. After checking the transmission, it is found that the locking clutch is burning black at the side. After repairing and missing the trouble code, the test run is done. The throttle is slightly larger, still not up to 4 gears. The electronic throttle setting is also invalid (setting method: A. off the ignition switch 15S above; B. to open the ignition switch 15S above; C. repeats A, B two times; D. quickly stepped on the throttle again; E. start vehicle 30min). Later, it was found that the ignition switch was turned off and the information center occasionally had ESP trouble. No fault code is detected in the system, but the right rear wheel speed signal of the read data stream is slightly smaller than that of other wheels. Inspection found that the right rear tire is not in conformity with the other tire specifications. Solution: replace the right rear tire.