Toyota 2GR-FE Manual page 356

ES–200
• When the total of the short-term and long-term fuel trim values is within the malfunction threshold (and
the engine coolant temperature is more than 75°C [167°F]), the system is functioning normally.
MONITOR DESCRIPTION
Under closed-loop fuel control, fuel injection volumes that deviate from those estimated by the ECM
cause changes in the long-term fuel trim compensation value. The long-term fuel trim is adjusted when
there are persistent deviations in the short-term fuel trim values. Deviations from the ECM's estimated fuel
injection volumes also affect the average fuel trim learning value, which is a combination of the average
short-term fuel trim (fuel feedback compensation value) and the average long-term fuel trim (learning
value of the air-fuel ratio). If the average fuel trim learning value exceeds the malfunction thresholds, the
ECM interprets this as a fault in the fuel system and sets a DTC.
Example:
The average fuel trim learning value is more than +35% or less than -35%, the ECM interprets this as a
fuel system malfunction.
ES
P0171 or P0174:
+35 (%)
Lean Malfunction Threshold
P0172 or P0175:
-35 (%)
Rich Malfunction Threshold
MONITOR STRATEGY
Related DTCs
Required Sensors / Components (Main)
Required Sensors / Components (Related)
Frequency of Operation
Duration
MIL Operation
Sequence of Operation
2GR-FE ENGINE CONTROL SYSTEM – SFI SYSTEM
Fuel Compensation Amount
1.35
1.0
0.65
P0171: Fuel trim Lean (Bank 1)
P0172: Fuel trim Rich (Bank 1)
P0174: Fuel trim Lean (Bank 2)
P0175: Fuel trim Rich (Bank 2)
Fuel system
A/F sensor, Mass air flow meter, Crankshaft position sensor
Continuous
Less than 10 seconds
2 driving cycles
None
A082386E30