What does the C1122 engine speed signal fault mean?
2 Answers
C1122 engine speed signal fault is likely due to an issue with the crankshaft sensor signal or a fault in the right front body acceleration sensor. Encountering this situation is a professional issue, a professional fault, and requires professional personnel to resolve; it is recommended to go to a 4S shop for computer diagnostics. Below is an introduction to the acceleration sensor: Acceleration sensor: includes a silicon diaphragm, upper cover, and lower cover, with the diaphragm positioned between the upper and lower covers, bonded together; one-dimensional or two-dimensional nanomaterials, gold electrodes, and leads are distributed on the diaphragm, and wires are drawn out using a bonding process. Function: The acceleration sensor is a testing instrument that converts the physical signal of acceleration into an easily measurable electrical signal. The differential capacitance force-balanced acceleration sensor converts the measured acceleration into changes in the capacitance of the capacitor.
The C1122 trouble code is quite common in cases I've handled. It indicates an issue with the engine speed signal, meaning the vehicle's computer isn't receiving accurate information about how fast the engine is rotating. Typically, this is caused by a faulty crankshaft position sensor - this small component located near the engine measures rotation speed and sends data to the ECU. In my repair experience, problems like sensor contamination, aged/cracked wiring, or loose connectors can all cause intermittent signals. When this occurs, the vehicle may experience hard starting, erratic tachometer readings, or even stalling while driving - which can be quite dangerous. If you encounter this, don't delay: first use an OBD scanner to confirm the code, then check if the sensor is covered by oil residue (clean it if necessary). If that doesn't work, inspect the wiring continuity or simply replace the sensor (costs about tens of dollars). Regular engine compartment checks and scheduled maintenance can help prevent this issue.