Throttle Position (TP) Sensor Intermittent The TP sensor circuit is monitored by the PCM for sudden TP rotation angle (or voltage) input change through the comprehensive component monitor (CCM). If during the last 80 warm-up cycles in key ON engine running the PCM detects a TP rotation angle (or voltage) changes beyond the minimum or maximum calibrated limit, a continuous diagnostic trouble code (DTC) is stored. Poor continuity through the TP sensor connectors Poor continuity through the TP harness Intermittent open or short inside the TP sensor While accessing the TP V PID on the scan tool, lightly tap on the TP sensor or wiggle the TP sensor connector and harness.
On some transmissions, such as automated manual transmissions or automatic transmissions with manual mode, the GSP switch lets the TCM know whether or not the driver has selected automatic or manual function. On manual transmissions, the GSP switch informs the TCM which gear the driver is selecting, and may function as a neutral safety switch, depending on system design. The TCM also uses the gate select position switch to monitor transmission operation. For example, if the driver selects manual mode and selects 3rd gear on an automatic transmission, the TCM may monitor speed sensors to detect clutch and brake slippage.
OBD C3994 code and tailpipe testing are two different approaches to identify vehicles in need of repair. The OBD system looks for broken or malfunctioning emissions control components and air suspension rear inflator solenoid output circuit open, while tailpipe tests sample a vehicle's exhaust to see if it is above or below certain prescribed limits. Given the robust nature of today's emissions control components, it is entirely possible for an individual component to C3994 malfunction without leading to an immediate increase in emissions at the tailpipe. In such cases, other components (like the catalyst) can temporarily compensate for the part that is broken however, these other components can only do double duty for so long before they, too, begin to malfunction. In addition, OBD also monitors for C3994 and other malfunctions in the fuel system problems that traditional tailpipe tests were not designed to identify. Most state and local areas also include a gas cap pressure test as part of an emission inspection.
Difficulty Level (Expert)
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Repair Time (60 Min.)
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Cost Prediction : $ 40-60 |
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C3994 is a kind of Chassis Trouble Code
Diagnosing chassis noises can be one of the most frustrating problems technicians face. Fortunately, manufacturers have engineered noise, vibration and harshness (NVH) diagnostic techniques and equipment to find the source of the noise. |
You can view according C3994 DTC for your car model. We selected several models to see obd2 solutions click and view it.