P0638

P0638 00

Throttle Mechanical, Throttle Position Deviation from Demanded







Fault symptom
- Check Engine
- No starter motor cranking.
- Engine does not start.
- Engine shut off.
- Limp home
- Cruise control not working.

On-board diagnosis

Type of diagnosis:
- Continuous

Enable criteria:
- Ignition ON.
- Throttle position not requested in rest position (position regulated by Trionic 8).

Fault criteria:
- When current throttle position deviates 10% from the requested position.

Dependent:
- None

System reaction to a fault:
- Correction of mass air flow/combustion for fuel calculation is blocked.
- Limited acceleration and idle function.
- Cruise control blocked.
- Secondary air switched off.

OK report:
- Fault criterion not fulfilled and vehicle speed over 0 km/h for more than 60 s.

Fault handling:
Type III
(See section Fault handling III, "Other emission-related components and functions" for more information.)

Checking the wiring harness
- Move the wiring harness at several spots and in several directions to reveal intermittent breaks and short-circuits. Check switches, connectors and crimp connections for oxidation, retracted pins and pin clamping force.

Diagnostic help

Diagnosis regards:
- Electrical fault in connecting leads or component.
- Mechanically binding/affected throttle.
- Approximately 3 to 5 seconds after Ignition on and non-actuated accelerator pedal, the throttle resumes rest position to conserve current.

Functions in the diagnostic tool related to the fault:

Test value:
- Throttle Position Sensor 1
- Throttle Position Sensor 2

Activation:
- Throttle Position Test
(See also description of readings/activations in diagnostic tool)