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Discussion Starter · #1 ·
OK I have a 2003 Ford Focus with roughly 71000 miles. This car has geiven me no problem in 3 years besides oil changes and about 2 weeks ago it started having the gauges fluctuate at various times..maybe 3 -5 times in 2 weeks. Now when this happens, the car does not jerk, stall or cut off?? Then after on eof the episodes, the engine light stayed on. Then my mechanically inclined husband..(love you D)..tried cleaning the battery cables and checked a couple of other things...and now because he unplugged the battery the light has went off and not come back on BUT now the car has a rougher idle to it and I just know something is not working correctly or is broken and it is only a matter of time...Also we did take it to Autozone (2 of them) when the check engine light came on and the first Autozone said that the code reader was could not read any codes so the problem had to be in the gear shift (It is an automatic) then the second Autozone said that it was my transmission??? I really dont think they knew what they were talking about??? Can someone please give me some sort of direction or clue.....Thanks[pray]

3,737 Posts
If you disconnect the battery, the computer will "forget" it's idle, and re-learn it as you drive. You can speed-up this relearning using the procedure in your owner's manual. If you do not have the manual, you can download one free at under the "maintenance" menu.

From the manual:

"Because your vehicle’s engine is electronically controlled by a computer,
some control conditions are maintained by power from the battery. When
the battery is disconnected or a new battery is installed, the engine must
relearn its idle and fuel trim strategy for optimum driveability and
performance. To begin this process:
1. With the vehicle at a complete stop, set the parking brake.
2. Put the gearshift in P (Park) (automatic transaxle) or the neutral
position (manual transaxle), turn off all accessories and start the engine.
3. Run the engine until it reaches normal operating temperature.
4. Allow the engine to idle for at least one minute.
5. Turn the A/C on and allow the engine to idle for at least one minute.
6. Drive the vehicle to complete the relearning process.
• The vehicle may need to be driven 10 miles (16 km) or more to
relearn the idle and fuel trim strategy.
• If you do not allow the engine to relearn its idle trim, the idle
quality of your vehicle may be adversely affected until the idle
trim is eventually relearned.
When the battery is disconnected or a new battery installed, the
transmission must learn its adaptive strategy. As a result of this, the
transmission may shift firmly. This operation is considered normal and
will fully update transmission operation to its optimum shift feel."
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