I recently had replaced the recalled gas tank and also replaced the fuel pump. with in 30 minutes the check engine lamp came on. Could it be the more efficient fuel pump that one of the codes has popped in.... I did notice that the idle speed has increased.


Code 12 - Airflow meter
Usually signals a problem with the airflow meter or the connector which can fall apart or become damaged. Refer to test 19, continuity test procedure.
Code 17 - Throttle potentiometer
Usually indicates a bad throttle position sensor. Refer to test 17, continuity test procedure.
Code 18 - Throttle potentiometer input high/airflow meter low
Usually indicates a problem with one of the two mentioned parts. Refer to tests 17, 18, and 19 of the continuity test procedure.

Code 19 - Throttle potentiometer input low/airflow meter high
Usually indicates a problem with one of the two mentioned parts. Refer to tests 17, 18, and 19 of the continuity test procedure.

Code 21 - Fuel tune select
Identifies that the tune select resistor is open circuit- refer to tune select resistor test. The tune resistor is embedded in the wire harness. This code may indicate damage to the wire harness.

Code 23 - Fuel supply
Check fuel system pressure, test 20 of continuity test procedure.

Code 25 - Ignition misfire
This code indicates that an ignition system misfire has been detected. Codes 40 or 50 indicate on which bank the misfire has occurred.

Code 28 - Air leak
One way to check for small leaks is by spraying choke cleaner at the joint you want to check while the motor is idling. A change in tone indicates the choke cleaner is being sucked into the engine. Check for air leaks in the following areas:
Hose, air flow meter to plenum
Breather system hoses to plenum
Brake servo hose
Vacuum reservoir hose (fresh air solenoid)
Distributor vacuum advance
Hose, purge valce to plenum
Injector seals
Joint - bypass air valve to plenum plenum chamber to ram housing ram housing to inlet manifold inlet manifold to cylinder head bypass air valve hose