Code 24
Code 24 is a diagnostic trouble code related to the Vehicle speed sensor circuit on the Pontiac Fiero.
Code 24 indicates that the ECM is not receiving the expected vehicle speed signal.
Overview
The vehicle speed sensor, often abbreviated as VSS, provides speed information used by the ECM and speedometer-related circuits.
The ECM uses vehicle speed information for functions such as idle control, deceleration behavior, fuel control, and drivability calculations.
Code 24 is set when the ECM detects an unexpected or missing vehicle speed signal under conditions where a speed signal should be present.
Flash pattern
Code 24 is displayed as:
- Two flashes
- Pause
- Four flashes
This represents code 24.
Animated flash pattern:
Meaning
Code 24 usually indicates a problem with the vehicle speed sensor signal or circuit.
Possible causes include:
- Faulty vehicle speed sensor
- VSS wiring problem
- Poor connector contact
- Speedometer circuit problem
- ECM input problem
- Damaged wiring between the VSS, speedometer, and ECM
- Speed sensor drive or transmission-related issue
Symptoms
Possible symptoms may include:
- Check engine light
- Speedometer problems
- Idle problems when slowing down or stopping
- Stalling during deceleration
- Poor drivability
- Cruise control problems, if equipped
- Little or no obvious drivability problem
Diagnosis
Basic diagnostic checks include:
- Confirm that Code 24 is present.
- Check whether the speedometer works correctly.
- Inspect the vehicle speed sensor connector.
- Inspect VSS wiring for damage.
- Check for poor connector contact or corrosion.
- Check for other stored trouble codes.
- Test the VSS signal if equipment is available.
- Check ECM and speedometer-related wiring if the sensor appears correct.
Speedometer relationship
On the Fiero, the vehicle speed signal is related to the speedometer system. A speedometer fault, wiring problem, or signal problem may affect ECM vehicle-speed input.
Related topics:
Notes
Code 24 should not automatically be treated as a failed vehicle speed sensor. Wiring, connectors, speedometer circuitry, and ECM input should also be considered.
A Code 24 may be especially noticeable if the engine stalls or behaves poorly when the car is slowing down or coming to a stop.