Sonata GL V6-3.0L (1997)
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On a Sonata, a one digit change of the "Long Term" Fuel Trim value is roughly the equivalent of one entire "Short Term" Fuel Trim range. For
example: when the "Short Term" Fuel Trim reaches its limit, the "Long Term" Fuel Trim moves one digit. This process repeats until the A/F ratio
returns to 14.7 to 1 or the "Long Term" Fuel Trim correction range limit has been exceeded.
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There is a preprogrammed "Long Term" Fuel Trim correction range that is acceptable for normal operation. When the "Long Term" Fuel Trim
exceeds this range in two driving cycles, the vehicle will set a diagnostic code (DTC), which will illuminate the check engine light.
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"Long Term" Fuel Trim values are retained in the PCM's memory when the ignition is turned off. This allows the vehicle to "learn" a new fuel
delivery schedule, which is "fine tuned" for optimal performance.
Oxygen Sensor Trim (Trim B1 S1 & Trim B1 S2
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Oxygen Sensor Trim is the PCM's response value to each individual oxygen sensor input. This value should change similar to the "Short Term" Fuel
Trim values and is not used for diagnostic purposes on Hyundai vehicles
Fuel Trim Diagnostic Codes
A Fuel Trim diagnostic code will set when Fuel Trim values exceed programmed limits due to either "Rich" or "Lean" operating conditions. The "Long
Term" or "Short Term" Fuel Trim numbers stored in the "Freeze Frame" data will indicate if the PCM was increasing or decreasing fuel delivery when
the code was set.
A PCM that is increasing fuel delivery (to compensate for a "Lean" condition) will have a positive (+) "Long Term" Fuel Trim number. A PCM that is
decreasing fuel delivery (to compensate for a "Rich" condition) will have a negative (-) "Long Term" Fuel Trim number.
Accent, Elantra & Tiburon Fuel Trim Codes
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The "Long Term" Fuel Trim correction range is -25% to +25% on Accent, Elantra and Tiburon. If the "Long Term" Fuel Trim value exceeds -20%
to +20% in two consecutive trips a code will be stored in the PCM.
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P1123 and P1124 are set at idle, low load and low engine speed operation. Codes set in these operating conditions are sometimes referred to as
additive Fuel Trim correction codes.
Note:
These codes are set when engine speed is less than approximately 1,000 rpm and the air flow sensor reading is less than 5 grams/sec.
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P1127 and P1128 are set at moderate to high engine load and engine speed operation. These codes are sometimes called multiplicative Fuel Trim
correction codes.
Sonata Fuel Trim Code
