Mazda DTC P2177 Diagnostic

DTC P2177	Fuel system too lean at off idle
DETECTION CONDITION	• PCM monitors short term fuel trim (SHRTFT), long term fuel trim (LONGFT) during closed loop fuel control at off-idle. If the LONGFT or the sum total of these fuel trims exceed preprogrammed criteria. PCM determines that fuel system is too lean at off-idle. Diagnostic support note • This is a continuous monitor. (FUEL SYSTEM) • MIL illuminates if PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM. • PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle. • FREEZE FRAME DATA is available. • DTC is stored in the PCM memory.
POSSIBLE CAUSE	• Misfire • Front HO2S deterioration • Front HO2S heater malfunction • MAF sensor malfunction • Pressure regulator (built-in fuel injection pump) malfunction • Fuel pump malfunction • Fuel filter clogged or restricted • Fuel leakage on fuel line from fuel delivery pipe and fuel pump • Leakage exhaust system • Purge solenoid valve improper operation • Purge solenoid valve malfunction (stuck open) • Purge solenoid hoses improper connection • Air suction in intake-air system • Insufficient engine compression

DTC P2177

Fuel system too lean at off idle

DETECTION CONDITION

• PCM monitors short term fuel trim (SHRTFT), long term fuel trim (LONGFT) during closed loop fuel control at off-idle. If the LONGFT or the sum total of these fuel trims exceed preprogrammed criteria. PCM determines that fuel system is too lean at off-idle.

Diagnostic support note

• This is a continuous monitor. (FUEL SYSTEM)

• MIL illuminates if PCM detects the above malfunctioning condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.

• PENDING CODE is available if PCM detects the above malfunction conditions during first drive cycle.

• FREEZE FRAME DATA is available.

• DTC is stored in the PCM memory.

POSSIBLE CAUSE

• Misfire

• Front HO2S deterioration

• Front HO2S heater malfunction

• MAF sensor malfunction

• Pressure regulator (built-in fuel injection pump) malfunction

• Fuel pump malfunction

• Fuel filter clogged or restricted

• Fuel leakage on fuel line from fuel delivery pipe and fuel pump

• Leakage exhaust system

• Purge solenoid valve improper operation

• Purge solenoid valve malfunction (stuck open)

• Purge solenoid hoses improper connection

• Air suction in intake-air system

• Insufficient engine compression

Diagnostic procedure


STEP	INSPECTION		ACTION
1	VERIFY FREEZE FRAME DATA HAS BEEN RECORDED • Has FREEZE FRAME DATA been recorded?	Yes	Go to the next step.
1		No	Record the FREEZE FRAME DATA on the repair order, then go to the next step.
2	VERIFY RELATED REPAIR INFORMATION AVAILABILITY • Verify related service repair information availability. • Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. • If the vehicle is not repaired, go to the next step.
2		No	Go to the next step.
3	VERIFY RELATED PENDING CODE OR STORED DTCS • Turn ignition switch to off, then the ON position (Engine off). • Verify related pending code or stored DTCs. • Is other DTC present?	Yes	If misfire DTC is present, go to Step 8. If other DTC is present, go to appropriate DTC troubleshooting procedure.
3		No	If drivability concern is present, go to Step 8. If not, go to the next step.
4	IDENTIFY TRIGGER DTC FOR FREEZE FRAME DATA • Is DTC P2177 on FREEZE FRAME DATA?	Yes	Go to the next step.
4		No	Go to troubleshooting procedures for DTC on FREEZE FRAME DATA.
5	VERIFY CURRENT INPUT SIGNAL STATUS (KEY TO ON/IDLE) • Access ECT, MAF, TP and VSS PIDs using WDS or equivalent. • Is there any signal that is far out of specification when key is ON and engine runs?	Yes	Inspect suspected sensor and excessive resistance in related wiring harnesses. Repair or if necessary. Then go to Step 16.
5		No	Go to the next step.
6	VERIFY CURRENT INPUT SIGANL STATUS UNDER TROUBLE CONDITION • Inspect same PIDs as Step 5 while simulating FREEZE FRAME DATA condition. • Is there any signal which causes drastic changes?	Yes	Inspect suspected sensor and related wiring harnesses repair or replace it. Then go to Step 16.
6		No	Go to the next step.
7	VERIFY CURRENT INUPUT SIGNAL STATUS OF FRONT HO2S • Access O2S11 PID using WDS or equivalent. • Check PID under following accelerator pedal condition (in PARK or NEUTRAL). • Is PID reading normal? – Above 0.45 V when accelerator pedal is suddenly depressed (rich condition). – Below 0.45 V just after release of accelerator pedal (lean condition).	Yes	Go to the next step.
7		No	Visually inspect for any gas leakage between exhaust manifold and front HO2S. Then go to Step 16.
8	VERIFY CURRENT INPUT SIGNAL STATUS OF MAF SENSOR • Connect the WDS or equivalent to the DLC-2. • Start the engine. • Access the MAF PID. • Verify that the MAF PID changes quickly according to engine speed. • Is the PID normal?	Yes	Go to the next step.
8		No	Replace MAF/IAT sensor, then go to Step 16.
9	INSPECT FOR EXCESSIVE AIR SUCTION OF INTAKE AIR SYSTEM • Visually inspect for loosen, cracks or damages hoses on intake-air system. • Is there any malfunction?	Yes	Repair or replace source of air suction, then go to Step 16.
9		No	Go to the next step.
10	INSPECT PURGE SOLENOID OPERATION • Carry out Purge Control System Inspection. • Does purge control system work properly?	Yes	Go to the next step.
10		No	Repair or replace malfunctioning part according to inspection result, then go to Step 16.
11	INSPECT FUEL LINE PRESSURE • Turn ignition switch to off. • Inspect fuel line pressure. • Is fuel line pressure normal?	Yes	Go to Step 12.
11		No	If fuel pressure is too high, replace fuel pump nit, then go to Step 16. If fuel line pressure is low, go to the next step.
12	INSPECT FUEL LINE FROM FUEL PUMP TO FUEL DELIVERY PIPE • Visually inspect fuel line for any leakage. • Is any fuel leakage found?	Yes	Replace suspected fuel line, then go to Step 16.
12		No	Inspect for foreign materials or stain inside fuel filter (low-pressure). If for foreign materials or stain inside fuel filter (low-pressure), clean of fuel tank and filter. Then go to Step 16.
13	INSPECT IGNITION SYSTEM • Carry out spark test. • Is strong blue spark visible at each cylinder?	Yes	Go to the next step.
13		No	Repair or replace malfunctioning part according to spark test result, then go to Step 16.
14	INSPECT ENGINE COMPRESSION • Inspect engine compression. • Is it normal?	Yes	Go to the next step.
14		No	Implement engine overhaul for repairs, then go to Step 16.
15	INSPECT FUEL INJECTOR OPERATION • Remove fuel injector. • Inspect fuel injector (resistance, injection amount). • Is fuel injector normal?	Yes	Go to the next step.
15		No	Replace suspected fuel injector, then go to the next step.
16	VERIFY TROUBLESHOOTING OF DTC P2177 COMPLETED • Make sure to reconnect all disconnected connectors. • Clear DTC from PCM memory using WDS or equivalent. • Perform the PCM Adaptive Memory Produce Drive Mode. • Is the PENDING CODE for this DTC present?	Yes	Replace PCM, then go to the next step.
16		No	Go to the next step.
17	VERIFY AFTER REPAIR PROCEDURE • Perform “After Repair Procedure”. • Is there any DTC present?	Yes	Go to the applicable DTC inspection.
17		No	Troubleshooting completed.