Acura RL (1996-2004 year). Manual - part 381

Fuel Supply System

Description
By monitoring the Long Term Fuel Trim, long term malfunctions in the fuel system will be detected.
If a malfunction has been detected during two consecutive trips, the MIL will come on and DTC P0171, P0172, P0174
and/or P0175 will be stored.

NOTE: If some of the DTCs listed below are stored at the same time as DTC P0171, P0172, P0174 and/or P0175, trou-
bleshoot those DTCs first, then troubleshoot DTC P0171, P0172, P0174 and/or P0175.

P0106*

, P0107, P0108, P1128*

, P1129*

: MAP Sensor

P0135: Right Primary HO2S Heater (Bank 1, Sensor 1)
P0137, P0138: Secondary HO2S (Sensor 2)
P0141: Secondary HO2S Heater (Sensor 2)
P0155: Left Primary HO2S Heater (Bank 2, Sensor 1)
P0401: EGR Flow Insufficient
P1491: EGR Valve Lift Insufficient
P1498: EGR Valve Position Sensor High Voltage
*1: '96 model only
*2: '97 - 01 models

DTC P0172, P0175
System too rich

• Fuel Pump insufficient flow/pressure
• Fuel Feed Line clogged, leaking
• Fuel Pressure Regulator stuck open
• Fuel Filter clogged
• Injector clogged, air inclusion
• Gasoline doesn't meet Owner's Manual spec.
• Primary HO2S (Sensor 1) deteriorated
• MAP Sensor range/performance*

• EGR System insufficient flow
• Exhaust leak

• Fuel Pressure Regulator clogged, stuck closed
• Fuel Return Pipe clogged
• Injector leaking
• Gasoline doesn't meet Owner's Manual spec.
• Primary HO2S (Sensor 1) deteriorated
• MAP Sensor range/performance*

• EGR System malfunction (too much flow)
• EVAP Canister Purge Valve leaking, stuck opened

DTCP0171, P0174

System too lean

The scan tool indicates Diagnostic Trouble Code (DTC) P0171: The fuel system is too lean [Right Bank (Bank 1)].

The scan tool indicates Diagnostic Trouble Code (DTC) P0172: The fuel system is too rich [Right Bank (Bank 1)].

The scan tool indicates Diagnostic Trouble Code (DTC) P0174: The fuel system is too lean [Left Bank (Bank 2)].

The scan tool indicates Diagnostic Trouble Code (DTC) P0175: The fuel system is too rich [Left Bank (Bank 2)].

Possible Cause

Main Menu

Table of Contents

PGM-FI System

Fuel Supply System (cont'd)

— The MIL has been reported on.
— DTC P0171, P0172, P0174 and/

or P0175 are stored.

Check the fuel pressure.

Is the fuel pressure OK?

YES

Check the Primary HO2S:

1. Start the engine. Hold the

engine at 3,000 rpm with no
load (in Park or neutral) until
the radiator fan comes on.

2. Check the right primary or left

primary* HO2S (Sensor 1) out-
put with the scan tool.

Is the fuel pressure too high
or too low?

Check the fuel pressure regulator
and fuel return pipe.

LOW

Check the fuel pump, fuel feed
pipe, fuel filter, and fuel pressure
regulator.

Does it stay at less than 0.3 V
or more than 0.6 V?

Replace the HO2S.

Check for a sticking or leaking
EVAP canister purge valve:
With a vacuum pump, apply vacu-
um to the EVAP canister purge
valve from the intake manifold
side.

Does it hold vacuum?

('96 model only)

Replace the EVAP canister purge
valve.

YES

Check the MAP sensor output:

1. Turn the ignition switch ON (II).

2. Check the MAP with the scan

tool.

Does it indicate atmospheric
pressure?

YES

*: P0174 or P0175

Check the response of the MAP
sensor:

1. Start the engine.

2. Check the MAP with the scan

tool.

Is a MAP of 40.0 kPa (300 mmHg,
12.0 inHg) or less indicated within
one second after starting the
engine?

Replace the MAP sensor.

YES

Check the EGR system. If it is OK,
replace the fuel injectors.

Replace the MAP sensor.

YES

HIGH

Troubleshooting Flowchart

Main Menu

Table of Contents

The scan tool indicates Diagnostic Trouble Code (DTC) P0325: A problem in the Right Knock Sensor (Bank 1) cir-

cuit.

The scan tool indicates Diagnostic Trouble Code (DTC) P0330: A problem in the Left Knock Sensor (Bank 2) cir-

cuit.

— The MIL has been reported on.
— DTC P0325 and/or P0330 are

stored.

Problem verification:
1. Do the PCM Reset Procedure.
2. Start the engine. Hold the

engine at 3,000 rpm with no

load (in Park or neutral) until

the radiator fan comes on,
then let it idle.

3. Hold the engine at 3,000 -

4,000 rpm for 10 seconds.

Is DTC P0325 and/or P0330
indicated?

YES

Check for a short in the wire

(knock sensor line):
1. Turn the ignition switch OFF.

2. Disconnect the knock sensor

sub-harness connector.

3. Check for continuity between

PCM connector terminals D2
or D13* and body ground.

Is there continuity?

Check for an open in the wire

(knock sensor line):
Check for continuity between PCM

connector terminal D2 or D13*
and knock sensor connector ter-
minal No. 1 or No. 3*.

Is there continuity?

YES

Substitute a known-good right or
left knock sensor and recheck.

Is DTC P0325 and/or P0330
indicated?

YES

Substitute a known-good PCM
and recheck (see page

11-42

for

immobilizer information). If symp-

tom/indication goes away, replace
the original PCM.

Intermittent failure, system is OK
at this time (test drive may be
necessary). Check for poor con-
nections or loose wires between
C251 (located at left shock

tower), C110 (located at left rear
corner of engine), C162*, C163

(knock sensor) and PCM.

PCM CONNECTOR D (22P)

Repair short in the wire between
PCM (D2 or D13*) and knock sen-
sor.

Wire side of female terminals

Repair open in the wire between
PCM (D2 or D13*) and knock sen-
sor.

KNOCK SENSOR

CONNECTOR

Replace the original knock sensor.

Wire side of female terminals

*: P0330

YES

Knock Sensor

Main Menu

Table of Contents

PGM-FI System

Misfire Detected in One Cylinder

The scan tool indicates Diagnostic Trouble Code (DTC) P1203 or P1303: Cylinder 3 misfire detected.

The scan tool indicates Diagnostic Trouble Code (DTC) P1204 or P1304: Cylinder 4 misfire detected.

The scan tool indicates Diagnostic Trouble Code (DTC) P1205 or P1305: Cylinder 5 misfire detected.

Description
Misfire detection is accomplished by monitoring the voltage of the spark plug with the spark plug voltage sensor which is
built into the ignition coil.

If misfiring strong enough to damage the catalyst is detected, the MIL will blink during the time of its occurrence, and a
misfire DTC will be stored. Then, after the misfire has ceased, the MIL will come on and stay on whenever the ignition

switch is ON (II).

If misfiring that increases emissions is detected during two consecutive driving cycles, the MIL will come on, and a misfire
DTC will be stored.

NOTE: If some of the DTCs listed below are stored at the same time as a misfire DTC, troubleshoot those DTCs first, then

troubleshoot the misfire DTC.

P0106*

, P1128*

, P1129*

: MAP sensor

P0171, P0172, P0174, P0175: Fuel supply system
P0401, P1491, P1498: EGR system
P1316, P1317, P1318, P1319: Spark Plug Voltage Detection System
P0335, P0336, P1336, P1337: CKP sensor
P1381, P1382, P1386, P1387: CYP sensor
*1: '96 model only
*2: '97 - 01 models

Possible Cause

Injector clogging, fuel leakage, air leakage
Injector circuit open or shorted
Injector resistor malfunction

Spark plug carbon deposits, fouling, malfunction
Ignition coil malfunction
ICM malfunction
Compression low

The scan tool indicates Diagnostic Trouble Code (DTC) P1206 or P1306: Cylinder 6 misfire detected.

The scan tool indicates Diagnostic Trouble Code (DTC) P1201 or P1301: Cylinder 1 misfire detected.

The scan tool indicates Diagnostic Trouble Code (DTC) P1202 or P1302: Cylinder 2 misfire detected.

Main Menu

Table of Contents

Content .. 379 380 381 382 ..