Here are the codes just in case you didn't have them.
Trouble Code 15 indicates that the Coolant Temperature Sensor (CTS) is reporting abnormally low readings. CTS is used to control fuel mixture, timing, idle speed, TCC and EGR operation, among others. The thermistor used has a high resistance when cold, lowering as the coolant warms. This error then, indicates a very high resistance in the CTS circuit.
The conditions for setting this code are:
the coolant temperature reported is < -29 deg F (-34 deg C), and
the above condition is present for more than 4 seconds
NOTE: A default temperature of 111 deg F is used while the error is present.
Refer to the Code 14 description for typical sensor resistance values.
Typical causes for this code include:
1) Open circuit in CTS-ECM harness
2) Defective Coolant Temperature Sensor (resistance too high)
3) Open sensor ground circuit
4) Defective ECM
Trouble Code 24 indicates that the Vehicle Speed Sensor (VSS) is reporting an abnormally low reading when other sensors indicate it should be higher.
The conditions for setting this code are:
no Code 33 or 34 (MAF Error) is present, and
the vehicle speed signal indicates < 4 MPH and
engine speed is between 1400 and 4400 RPM, and
during a low load condition (LV8 between 50 and 99), and
transmission not in Park or Neutral, and
all conditions met for more than 20 seconds
If the code was logged when the vehicle was in motion, the following should be checked:
1) Defective or corroded VSS connections
2) Maladjusted TPS sensor. The TPS should read about 0.42 volts at closed throttle
3) Defective speedometer cable
4) Bad or missing speedo drive gear(s) in tail shaft housing of the transmission
5) Defective VSS
6) Defective ECM
Trouble Code 25 indicates that the Manifold Air Temperature (MAT) sensor is reporting abnormally high readings. When the air is hot, the thermistor has a low resistance, which rises as the air temperature cools. High readings thus indicate a possible bad sensor or short in the MAT circuit.
The conditions for setting this code are:
MAT reading is > 275 deg F (135 deg C), and
the engine has been running for more than 16 seconds, and
the vehicle speed is > 40 MPH
Refer to the Code 23 description for typical sensor resistance values.
Typical causes for this code include:
1) Defective MAT sensor
2) MAT signal shorted to ground or to sensor ground
3) Defective ECM