Fuel System Monitor
OBD System Description - Fuel System MonitorFueltrim_B1_Lean
DTC Description / Detecting Condition / Confirmation Procedure
P0171 refer to [DTC P0171: Fuel Trim System Lean]. P0171
Monitor Strategy Description
Determines when the Fuel control is trying to respond to a very lean system, and has reached the limit of its control authority.
Malfunction Criteria
Primary Fuel Control in current BLM Cell >= 1.29999 Mult
Enable Conditions
Current BLM Cell is enabled for diagnostic = TRUE
AND Disabling Fault Present (refer to disabling fault list, included with certification documentation) = FALSE
AND Off-board Device control active = FALSE
AND Barometric Pressure >= 72 kPa
AND Intake Air Temperature >= -40 °C
AND Ignition Voltage ->= 10 V
AND Fuel Learn Enable (diagnostic will run when Fuel Control adjustments are enabled) = TRUE
NOTE: Fuel Learn Enable TRUE if: = TRUE
Primary Fuel Control Active? = FALSE
AND Evap Purge is inhibiting Primary Fuel Control learning?
Time required
Current Excursion timer exceeds threshold
See table below.
AND THEN
Fail counter for current BLM Cell exceeds threshold
See table below.
Diagnostic must pass in 3 BLM Cells to report a pass after a non-volatile memory clear
See table below.
sample counts required to pass a BLM Cell
Fueltrim_B1_Rich
DTC Description / Detecting Condition / Confirmation Procedure
P0172 refer to [DTC P0172: Fuel Trim System Rich]. P0172
Monitor Strategy Description
Determines when the Fuel control is trying to respond to a very rich system, and has reached the limit of its control authority.
Malfunction Criteria
Primary Fuel Control in current BLM Cell <= 0.70001 Mult
Enable Conditions
Current BLM Cell is enabled for diagnostic = TRUE
AND Disabling Fault Present (refer to disabling fault list, included with certification documentation) = FALSE
AND Off-board Device control active = FALSE
AND Barometric Pressure >= 72 kPa
AND Intake Air Temperature >= -40 °C
AND Ignition Voltage ->= 10 V
AND Fuel Learn Enable (diagnostic will run when Fuel Control adjustments are enabled) = TRUE
NOTE: Fuel Learn Enable TRUE if: = TRUE
Primary Fuel Control Active? = FALSE
AND Evap Purge is inhibiting Primary Fuel Control learning?
Time required
Current Excursion timer exceeds threshold
See table below.
AND THEN
Fail counter for current BLM Cell exceeds threshold
See table below.
Diagnostic must pass in 3 BLM Cells to report a pass after a non-volatile memory clear
See table below.
sample counts required to pass a BLM Cell
Fueltrim_B1_ICO_Lean
DTC Description / Detecting Condition / Confirmation Procedure
P2187 refer to [DTC P2187: Fuel Trim System Lean at Idle]. P2187
Monitor Strategy Description
Determines when the Fuel control is trying to respond to a very lean system, and has reached the limit of its control authority at Idle conditions.
Malfunction Criteria
Long-Term Fuel Control in current BLM Cell has reached limit of lean system adjustment, and has remained there for the calibrated length of time. >= 1.29999 Mult.
Enable Conditions
Current BLM Cell is enabled for diagnostic = TRUE
AND Disabling Fault Present = FALSE
(refer to disabling fault list, included with certificationdocumentation) = FALSE
AND Off-board Device control active = FALSE
AND Barometric Pressure >= 72 kPa
AND Intake Air Temperature >= -40 °C
AND Ignition Voltage >= 10 V
AND Fuel Learn Enable (diagnostic will run when Fuel Control adjustments are enabled) = TRUE
NOTE: Fuel Learn Enable TRUE if:
Primary Fuel Control Active? = TRUE
AND Evap Purge is inhibiting Primary Fuel Control learning? = FALSE
Time required
FAIL:
Current Excursion timer exceeds threshold
See table below.
AND THEN
Fail counter for current BLM Cell exceeds threshold
See table below.
PASS:
Diagnostic must pass in 1 BLM Cells to report a pass after a non-volatile memory clear
See table below.
sample counts required to pass a BLM Cell
Fueltrim_B1_ICO_Rich
DTC Description / Detecting Condition / Confirmation Procedure
P2188 refer to [DTC P2188: Fuel Trim System Rich at Idle]. P2188
Monitor Strategy Description
Determines when the Fuel control is trying to respond to a very rich system, and has reached the point of emissions impact at Idle conditions.
Malfunction Criteria
Long-Term Fuel Control in current BLM Cell has reached limit of rich system adjustment, and has remained there for the calibrated length of time. <= 0.70001 Mult.
Enable Conditions
Current BLM Cell is enabled for diagnostic = TRUE
AND Disabling Fault Present = FALSE
(refer to disabling fault list, included with certification documentation) = FALSE
AND Off-board Device control active = FALSE
AND Barometric Pressure >= 72 kPa
AND Intake Air Temperature >= -40 °C
AND Ignition Voltage >= 10 V
AND Fuel Learn Enable (diagnostic will run when Fuel Control adjustments are enabled) = TRUE
NOTE: Fuel Learn Enable TRUE if:
Primary Fuel Control Active? = TRUE
AND Evap Purge is inhibiting Primary Fuel Control learning? = FALSE
Time required
Current Excursion timer exceeds threshold
See table below.
AND THEN
Fail counter for current BLM Cell exceeds threshold
See table below.
Diagnostic must pass in 1 BLM Cells to report a pass after a non-volatile memory clear
See table below.
sample counts required to pass a BLM Cell
Fueltrim_B1_PostO2_Learn
DTC Description / Detecting Condition / Confirmation Procedure
P2096 refer to [DTC P2096: Post Catalyst Fuel Trim System Low Limit]. P2096
Monitor Strategy Description
Determines when the Rear Fuel trim is trying to respond to a very lean system, and has reached the limit of its control authority.
Malfunction Criteria
Rear Sensor Primary Closed-Loop long-term fueling adjustment has reached its limit of authority.
= TRUE
AND
Rear Sensor Voltage is still trying to move the adjustment further in the same direction. < See table below
Enable Conditions
Current BLM Cell is enabled for diagnostic = TRUE
Disabling Faults Present = FALSE
(refer to disabling fault list, included with certification documentation) = FALSE
AND Off-board Device control active = FALSE
AND Barometic Pressure >= 72 kPa
AND Intake Air Temperature >= -40 °C
AND Ignition Voltage >= 10 V
AND Fuel Learn Enable (for Rear Sensor-based adjustments) = TRUE
(P diagnostic will run when Fuel Control adjustments are enabled)
Time required
Current Excursion timer exceeds threshold
See table below.
AND THEN
Fail counter for current BLM Cell exceeds threshold
See table below.
Diagnostic must pass in 2
BLM Cells to report a pass after a non-volatile memory clear
See table below.
sample counts required to pass a BLM Cell.
Fueltrim_B1_PostO2_Rich
DTC Description / Detecting Condition / Confirmation Procedure
P2097 refer to [DTC P2097: Post Catalyst Fuel Trim System High Limit]. P2097
Monitor Strategy Description
Determines when the Rear Fuel trim is trying to respond to a very rich system, and has reached the limit of its control authority.
Malfunction Criteria
Rear Sensor Primary Closed-Loop long-term fueling adjustment has reached its limit of authority.
= TRUE
AND
Rear Sensor Voltage is still trying to move the adjustment further in the same direction. = See table below.
Enable Conditions
Current BLM Cell is enabled for diagnostic = TRUE
Disabling Faults Present = FALSE
(refer to disabling fault list, included with certification documentation) = FALSE
AND Off-board Device control active = FALSE
AND Barometic Pressure >= 72 kPa
AND Intake Air Temperature >= -40 °C
AND Ignition Voltage >= 10 V
AND Fuel Learn Enable (for Rear Sensor-based adjustments) = TRUE
(diagnostic will run when Fuel Control adjustments are enabled)
Time required
Current Excursion timer exceeds threshold
See table below.
AND THEN
Fail counter for current BLM Cell exceeds threshold
See table below.
Diagnostic must pass in 2
BLM Cells to report a pass after a non-volatile memory clear
See table below.
sample counts required to pass a BLM Cell.
