DTC 2-2-1 Long Term Fuel Trim, Part Load, Lower Limit

2-2-1 LONG TERM FUEL TRIM, PART LOAD, UPPER LIMIT

Condition(s) for DTCs
^ The MFI module receives information from the Heated Oxygen Sensor (HO2S) if the air/fuel mixture is too lean in the idling range (2-3-2) or in the part-load range (2-2-1). In this case, the HO2S signal will usually be less than 0.5 Volts. The MFI module short term fuel trim compensates for this by enriching the mixture so to maintain a value of Lambda = 1. Deviation of the short term fuel trim mid-setting from its normal value will be compensated by the long term fuel trim. Enrichment by the long term almost to a maximum (upper limit) will be interpreted as abnormal and the DTC will be recorded.

Substitute value
^ None.

Fault source(s)
^ Open-circuit in HO2S heater supply or signal lead.
^ HO2S heater signal lead short-circuited to ground or supply.
^ Faulty HO2S.
^ Contact resistance and oxidation in HO2S connector.
^ Faulty Mass Air Flow (MAF) Sensor.
^ Low fuel pressure.
^ Air leakage.
^ Incorrect sensor signals.

Fault symptom(s)
^ May cause high fuel consumption.
^ May cause impaired performance.