P1400

DPFE Sensor Low Voltage (Mazda)

P1400

DPFE Sensor Low Voltage (Ford)

P1401

DPFE Sensor High Voltage (Mazda)

P1401

DPFE Sensor High Voltage (Ford)

P1403

DPFE Hoses Reversed (Mazda)

P1403

No 5 Volts To EGR Sensor (Chrysler)

P1404

Exhaust Gas Recirculation (EGR) Valve Pintle Stuck Open

P1405

DPFE Upstream Hose Off Or Plugged (Mazda)

P1405

DPFE Upstream Hose Off Or Plugged (Ford)

P1406

DPFE Downstream Hose Off Or Plugged (Mazda)

P1406

DPFE Downstream Hose Off Or Plugged (Ford)

P1407

EGR No Flow Detected (Mazda)

P1408

EGR Out Of Self Test Range (Mazda)

P1408

EGR Out Of Self Test Range (Ford)

P1409

Electronic Vacuum Regulator Control Circuit Malfunction (Mazda)

P1409

EGR Vacuum Regulator Solenoid Circuit Malfunction (Ford)

P1411

Secondary Air Injection System Downstream Flow (Ford)

P1413

Secondary Air Injection System Monitor Circuit Low (Ford)

P1414

Secondary Air Injection System Monitor Circuit High (Ford)

P1432

THTRC Circuit Failure (Ford)

P1441

Evaporative System Flow During Non-Purge

P1443

Evaporative Emission Control System (Mazda)

P1443

Small Or No Purge Flow Condition (Ford)

P1444

Purge Flow Sensor Low Input (Mazda)

P1445

Purge Flow Sensor High Input (Mazda)

P1450

Unable To Bleed Up Fuel Tank Vacuum (Ford)

P1451

EVAP Control System Canister Vent Solenoid Circuit Malfunction (Ford)

P1457

Leak Detected In EVAP Control Sys.(EVAP Canister Sys.) (Acura)

P1460

WOT A/C Cutoff Circuit Malfunction (Mazda)

P1460

WOT A/C Cutoff Circuit Malfunction (Ford)

P1461

ACP Sensor High Voltage (Ford)

P1462

ACP Sensor Low Voltage (Ford)

P1463

ACP Sensor Insufficent Pressure Change (Ford)

P1464

A/C Demand Out Of Range (Ford)

P1469

Low A/C Cycling Period (Ford)

P1474

HCF Primary Circuit Failure (Ford)

P1474

LFC Primary Circuit Failure (Ford)

P1476

Too Little Secondary Air (Chrysler)

P1477

Too Much Secondary Air (Chrysler)

P1477

MFC Primary Circuit Failure (Ford)

P1478

Battery Temp Sensor Volts Out of Limit (Chrysler)

P1479

HFC Primary Circuit Failure (Ford)

P1479

Transmission Fan Relay Circuit (Chrysler)

P1480

PCV Solenoid Valve (Chrysler)

P1482

Catalyst Temperature Sensor Circuit Shorted Low (Chrysler)

P1483

Engine Cooling System Performance

P1483

Catalyst Temperature Sensor Circuit Shorted High (Chrysler)

P1484

Catalytic Converter overheat Detected (Chrysler)

P1485

Air Injection Solenoid Circuit (Chrysler)

P1486

Evap Leak Monitor Pinched Hose (Chrysler)

P1487

Hi Speed Rad Fan CTRL Relay Circuit (Chrysler)

P1488

Auxiliary 5 Volt Supply Output Too Low (Chrysler)

P1489

High Speed Fan CTRL Relay Circuit (Chrysler)

P1490

Low Speed Fan CTRL Relay Circuit (Chrysler)

P1491

Rad Fan Control Relay Circuit (Chrysler)

P1491

Malfunction In EGR System (Acura)

P1492

Ambient/Batt Temp Sen Volts Too High (Chrysler)

P1493

Ambient/Batt Temp Sen Volts Too Low (Chrysler)

P1494

Leak Detection Pump Switch or Mechanical Fault (Chrysler)

P1495

Leak Detection Pump Solenoid Circuit (Chrysler)

P1496

5 Volt Supply Output Too Low (Chrysler)

P1498

High speed Rad Fan Ground CTRL Rly Circuit (Chrysler)

P1498

Voltage Problem In EGR Valve Position Sensor Circuit (Acura)

System Too Lean – Bank 1

Description:

How does a P0171 code trigger the check engine light? This code will trigger the check engine light as follows:

The adaptive fuel strategy in the vehicle’s computer constantly monitors the fuel delivery system to make sure the engine is running at an optimum air to fuel ratio, which is 14.7:1. The computer adjusts injector pulse width to regulate the amount of fuel going into the engine. The oxygen sensors relay information to the Powertrain Control Module (computer), informing it of the oxygen content in the exhaust. This information is translated by the computer, and used to determine if more or less fuel is needed. The computer will then adjust fuel flow (and possibly other related engine operating characteristics), to keep the correct air fuel mixture. This loop continues as long as the engine is running. Please refer to our article Oxygen Sensor Code Diagnosis for more info on this system. A P0171 check engine light code is set when the computer has reached a rich calibration limit and can not add enough fuel to maintain the correct mixture.

Possible Causes:

Refer to our Oxygen Sensor Code Diagnosis article for a list of all possible causes. The following is an overview of P0171 check engine light code possible causes.

Fuel System:

Leaking or faulty fuel pressure regulator
Plugged or dirty fuel filter or lines
Fuel pump weak or defective check valve
Injectors leaking or faulty
Low fuel pressure or running out of fuel
Leaking EVAP system components
Faulty FRP (Fuel Rail Pressure Sensor)

Air Intake System

Vacuum leaks
Contaminated, damaged or faulty Mass Air Flow sensor
PCV valve leak or stuck open
Air induction turbulance caused by wrong filter
Oil dipstick not seated
Air leaks after the Mass Air Flow Sensor (MAF)
Oil coated aftermarket air filter

Exhaust System

Any exhaust leak before or near the oxygen sensors

EGR System

Vacuum line disconnected from EGR System Module (ESM)
EGR valve, tube or gasket leak
EGR vacuum regulator valve leaking

Secondary Air Injection System

Mechanically stuck secondary air injection valve

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