Action Taken When the DTC Sets - Type A
The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails.
Action Taken When the DTC Sets - Type B
The control module illuminates the MIL on the second consecutive ignition cycle that the diagnostic runs and fails.
Conditions for Clearing the MIL/DTC - Type A or Type B
- The control module turns OFF the MIL after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
- A current DTC Last Test Failed clears when the diagnostic runs and passes.
- Use a scan tool in order to clear the MIL and the DTC.
Action Taken When the DTC Sets - Type C
- The control module stores the DTC information into memory when the diagnostic runs and fails.
- The MIL will not illuminate.
- The driver information center, if equipped, may display a message.
Conditions for Clearing the DTC - Type C
- A last test failed, or current DTC, clears when the diagnostic runs and passes.
- Use a scan tool in order to clear the DTC.
Conditions for Clearing the DTC - Type X
This DTC is available in the PCM software, but has been disabled, or turned OFF. In this case, the diagnostic does not run, no DTCs are stored, and the MIL does not illuminate. Type X DTCs are used primarily for export vehicles that do not require MIL illumination or DTC storing.
Diagnostic Trouble Code (DTC) Type(s)
| Description | Federal and California Emissions, (NC1, NF2) 4.3L LU3 | Unleaded Fuel Export (NF9) 4.3L LU3 |
|---|---|---|
| DTC P0016 | B | B |
| DTC P0101 | B | B |
| DTC P0102 | B | B |
| DTC P0103 | B | B |
| DTC P0106 | B | B |
| DTC P0107 | B | B |
| DTC P0108 | B | B |
| DTC P0112 | B | B |
| DTC P0113 | B | B |
| DTC P0116 | B | B |
| DTC P0117 | B | B |
| DTC P0118 | B | B |
| DTC P0121 | B | B |
| DTC P0122 | B | B |
| DTC P0123 | B | B |
| DTC P0125 | B | B |
| DTC P0128 | B | B |
| DTC P0131 | B | B |
| DTC P0132 | B | B |
| DTC P0133 | B | B |
| DTC P0134 | B | B |
| DTC P0135 | B | B |
| DTC P0137 | B | B |
| DTC P0138 | B | B |
| DTC P0140 | B | B |
| DTC P0141 | B | B |
| DTC P0151 | B | B |
| DTC P0152 | B | B |
| DTC P0153 | B | B |
| DTC P0154 | B | B |
| DTC P0155 | B | B |
| DTC P0157 | B | B |
| DTC P0158 | B | B |
| DTC P0160 | B | B |
| DTC P0161 | B | B |
| DTC P0171 | B | B |
| DTC P0172 | B | B |
| DTC P0174 | B | B |
| DTC P0175 | B | B |
| DTC P0200 | B | B |
| DTC P0218 | C | C |
| DTC P0230 | B | B |
| DTC P0300 | B | B |
| DTC P0315 | A | A |
| DTC P0325 | B | B |
| DTC P0327 | B | B |
| DTC P0335 | B | B |
| DTC P0336 | B | B |
| DTC P0341 | B | B |
| DTC P0351 | B | B |
| DTC P0420 | A | A |
| DTC P0430 | A | A |
| DTC P0442 | A | X |
| DTC P0443 | B | B |
| DTC P0446 | A | A |
| DTC P0449 | B | B |
| DTC P0452 | B | B |
| DTC P0453 | B | B |
| DTC P0455 | A | A |
| DTC P0461 | C | C |
| DTC P0462 | C | C |
| DTC P0463 | C | C |
| DTC P0496 | B | B |
| DTC P0500 | B | B |
| DTC P0502 | B | B |
| DTC P0503 | B | B |
| DTC P0506 | B | B |
| DTC P0507 | B | B |
| DTC P0522 | C | C |
| DTC P0523 | C | C |
| DTC P0530 | C | C |
| DTC P0562 | C | C |
| DTC P0563 | C | C |
| DTC P0601 | A | A |
| DTC P0602 | A | A |
| DTC P0604 | A | A |
| DTC P0608 | C | C |
| DTC P0609 | C | C |
| DTC P0641 | B | B |
| DTC P0650 | B | B |
| DTC P0651 | B | B |
| DTC P0654 | C | C |
| DTC P0704 | B | B |
| DTC P0706 | C | C |
| DTC P0711 | C | C |
| DTC P0712 | C | C |
| DTC P0713 | C | C |
| DTC P0719 | C | C |
| DTC P0724 | C | C |
| DTC P0740 | B | B |
| DTC P0741 | B | B |
| DTC P0742 | B | B |
| DTC P0748 | C | C |
| DTC P0751 | B | B |
| DTC P0752 | B | B |
| DTC P0753 | B | B |
| DTC P0756 | A | A |
| DTC P0757 | A | A |
| DTC P0758 | A | A |
| DTC P0785 | B | B |
| DTC P0894 | B | B |
| DTC P1106 | C | C |
| DTC P1107 | C | C |
| DTC P1111 | C | C |
| DTC P1112 | C | C |
| DTC P1114 | C | C |
| DTC P1115 | C | C |
| DTC P1121 | C | C |
| DTC P1122 | C | C |
| DTC P1133 | B | B |
| DTC P1153 | B | B |
| DTC P1380 | C | X |
| DTC P1381 | C | X |
| DTC P1626 | C | C |
| DTC P1631 | C | C |
| DTC P1637 | C | C |
| DTC P1638 | C | C |
| DTC P1683 | B | B |
| DTC P1810 | B | B |
| DTC P1860 | B | B |
| DTC P1875 | B | B |
| DTC U1026 | C | C |
| DTC U1041 | C | C |
| DTC U1056 | C | C |
| DTC U1064 | C | C |
| DTC U1300 | C | C |
| DTC U1301 | C | C |
Diagnostic Trouble Code (DTC) Type(s)
Scheme 420
| Callout | Component Name |
|---|---|
| 1 | Manifold Absolute Pressure (MAP) Sensor |
| 2 | EVAP Canister Purge Hose |
| 3 | EVAP Service Port |
| 4 | Positive Crankcase Ventilation (PCV) Valve |
| 5 | Throttle Body |
| 6 | EVAP Canister Purge Valve |
| 7 | AIR Module, if equipped |
Scheme 421
| Callout | Component Name |
|---|---|
| 1 | EVAP Canister Purge Solenoid Valve |
| 2 | EVAP Canister |
| 3 | Fuel Fill Neck/Fill Cap |
| 4 | Rollover Valve/Fuel Tank Pressure (FTP) Sensor |
| 5 | Fuel Tank |
| 6 | EVAP Canister Vent Solenoid Valve |
| 7 | Vent Hose/Pipe |
| 8 | EVAP Vapor Pipe |
| 9 | EVAP Purge Pipe |
| 10 | EVAP Service Port |
Scheme 422
| Callout | Component Name |
|---|---|
| 1 | Engine Compartment Fuel Pipes |
| 2 | Fuel Return Pipe |
| 3 | Fuel Feed Pipe |
| 4 | Fuel Filter |
Cleaning and Inspection Procedure
Clean the IAC valve O-ring sealing surface, pintle valve seat, and air passage.
- Remove any excess carbon deposits with a small amount of carburetor cleaner on a parts cleaning brush. Follow any instructions on the cleaner container regarding cleaner usage.
- Do not use a cleaner containing an extremely powerful solvent such as methyl ethyl ketone.
- Shiny spots on the pintle and seat do not represent a bent or misaligned pintle shaft.
- If heavy deposits are present in the air passage, remove the throttle body for a complete cleaning. Refer to «Throttle Body Cleaning Procedure»(ref-184141-S39471742082005082200000) .
Distributor Inspection
| IMPORTANT | Discoloration of the distributor cap and some whitish build up around the cap terminals is normal. Yellowing of the cap, darkening and some carbon build up under the rotor segment is normal. Replacement of the cap and rotor is not necessary unless there is a driveability concern. |
- Inspect the distributor cap for cracks, tiny holes or carbon tracks between the cap terminal traces. Diagnose the carbon tracks using the following procedure: Remove the spark plug wires from the distributor cap. Twist each spark plug boot 1/2 turn. Pull only on the wire boot in order to remove the wire from the cap. Disconnect the electrical connector from the base of the distributor. Remove the distributor cap screws and cap. Place 1 lead from the digital multimeter (DMM) on a cap terminal. Use the other lead in order to probe all other terminals and the center carbon ball. Move the base lead to the next terminal. Probe all other leads. Continue this procedure until you test all the secondary terminals. If there are any non-infinite readings, replace the cap.
- Inspect the cap for excess build-up of corrosion on the terminals. Scrape clean the terminals. Replace the cap if the corrosion is excessive. Some buildup is normal
- Inspect the rotor segment for excess wear. Replace the rotor if excess looseness in the rotor segment is present.
- Inspect the shaft for shaft-to-bushing looseness: Inspect the housing for cracks or damage. Insert the shaft in the housing. If the shaft wobbles, replace the housing.
Spark Plug Wire Inspection
Spark plug wire integrity is vital for proper engine operation. A thorough inspection is necessary to accurately identify conditions that may affect engine operation. Inspect for the following conditions
- Correct routing of the spark plug wires. Incorrect routing may cause cross-firing.
- Any signs of cracks or splits in the wires.
- Inspect each boot for the following conditions: Tearing Piercing Arcing Corroded terminal
If corrosion, or arcing are indicated on a spark plug wire boot a terminal, replace the wire and inspect the components connected to the wire.
Spark Plug Inspection
- Verify that the correct spark plug is installed. An incorrect spark plug causes driveability conditions. Refer to «Ignition System Specifications»(ref-184136-S08279977642005082200000) for the correct spark plug.
- Ensure that the spark plug has the correct heat range. An incorrect heat range causes the following conditions: Spark plug fouling-Colder plug Pre-ignition causing spark plug and/or engine damage-Hotter plug
- Inspect the terminal post (1) for damage. Inspect for a bent or broken terminal post (1). Test for a loose terminal post (1) by twisting and pulling the post. The terminal post (1) should not move.
- Inspect the insulator (2) for flashover, carbon tracking, or soot. This is caused by the electrical charge traveling across the insulator (2) between the terminal post (1) and ground. Inspect for the following conditions: Inspect the spark plug boot for damage. Inspect the spark plug recess area of the cylinder head for moisture, such as oil, coolant, or water. A spark plug boot that is saturated causes arcing to ground.
- Inspect the insulator (2) for cracks. All or part of the electrical charge may arc through the crack instead of the electrodes (3, 4).
- Inspect for evidence of improper arcing. Measure the gap between the center electrode (4) and the side electrode (3) terminals. Refer to «Ignition System Specifications»(ref-184136-S08279977642005082200000) . An excessively wide electrode gap can prevent correct spark plug operation. Inspect for the correct spark plug torque. Refer to «Ignition System Specifications»(ref-184136-S08279977642005082200000) . Insufficient torque can prevent correct spark plug operation. An over torqued spark plug, causes the insulator (2) to crack. Inspect for signs of tracking that occurred near the insulator tip instead of the center electrode (4). Inspect for a broken or worn side electrode (3). Inspect for a broken, worn, or loose center electrode (4) by shaking the spark plug. A rattling sound indicates internal damage. A loose center electrode (4) reduces the spark intensity. Inspect for bridged electrodes (3, 4). Deposits on the electrodes (3, 4) reduce or eliminates the gap. Inspect for worn or missing platinum pads on the electrodes (3, 4), if equipped. Inspect for excessive fouling.
- Inspect the spark plug recess area of the cylinder head for debris. Dirty or damaged threads can cause the spark plug not to seat correctly during installation.
Visual Inspection
- Normal operation-Brown to grayish tan with small amounts of white powdery deposits are normal combustion by-products from fuels with additives.
- Carbon fouled-Dry, fluffy black carbon, or soot caused by the following conditions: Rich fuel mixtures Leaking fuel injectors Excessive fuel pressure Restricted air filter element Incorrect combustion Reduced ignition system voltage output Weak ignition coils Worn ignition wires Incorrect spark plug gap Excessive idling or slow speeds under light loads can keep spark plug temperatures so low that normal combustion deposits may not burn off.
- Deposit fouling-Oil, coolant, or additives that include substances such as silicone, very white coating, reduces the spark intensity. Most powdery deposits will not affect spark intensity unless they form into a glazing over the electrode.
Diagnostic Trouble Codes (DTCs)
The powertrain control module (PCM) is programmed with test routines that test the operation of the various systems the PCM controls. Some tests monitor internal PCM functions. Many tests are run continuously. Other tests run only under specific conditions, referred to as Conditions for Running the DTC. When the vehicle is operating within the conditions for running a particular test, the PCM monitors certain parameters and determines if the values are within an expected range. The parameters and values considered outside the range of normal operation are listed as Conditions for Setting the DTC. When the Conditions for Setting the DTC occur, the PCM executes the Action Taken When the DTC Sets. Some DTCs alert the driver via the malfunction indicator lamp (MIL) or a message. Other DTCs do not trigger a driver warning, but are stored in memory. The PCM also saves data and input parameters when most DTCs are set. This data is stored in the Freeze Frame and/or Failure Records.
The DTCs are categorized by type. The DTC type is determined by the MIL operation and the manner in which the fault data is stored when a particular DTC fails. In some cases there may be exceptions to this structure. Therefore, when diagnosing the system it is important to read the Action Taken When the DTC Sets and the Conditions for Clearing the DTC in the supporting text.
There are different types of DTCs and different actions taken when the DTCs set. Refer to Diagnostic Trouble Code (DTC) Type Definitions for a description of the general characteristics of each DTC type.
DTC Status
When the scan tool displays a DTC, the status of the DTC is also displayed. The following DTC statuses are indicated only when they apply to the DTC that is set.
Large Leak Test
This tests for large leaks and blockages in the evaporative emission (EVAP) system. The control module commands the EVAP vent solenoid valve ON and commands the EVAP purge solenoid valve ON, with the engine running, allowing engine vacuum into the EVAP system. The control module monitors the fuel tank pressure (FTP) sensor voltage to verify that the system is able to reach a predetermined level of vacuum within a set amount of time. The control module then commands the EVAP purge solenoid valve OFF, sealing the system, and monitors the vacuum level for decay. If the control module does not detect that the predetermined vacuum level was achieved, or the vacuum decay rate is more than a calibrated level on 2 consecutive tests, DTC P0455 will set.
Small Leak Test
The engine off natural vacuum (EONV) diagnostic is the small-leak detection diagnostic for the evaporative emission (EVAP) system. While previous leak detection methods were performed with the engine running, the EONV diagnostic monitors the EVAP system pressure or vacuum with the ignition OFF. Because of this, it may be normal for the control module to remain active for up to 40 minutes after the ignition is turned OFF. This is important to remember when performing a parasitic draw test on vehicles equipped with EONV.
The EONV utilizes the temperature changes in the fuel tank immediately following a drive cycle to use the naturally occurring vacuum or pressure in the fuel tank. When the vehicle is driven, the temperature rises in the tank. After the vehicle is parked, the temperature in the tank continues to rise for a period of time, then starts to drop. The EONV diagnostic relies on this temperature change and the corresponding pressure change in a sealed system, to determine if an EVAP system leak is present.
The EONV diagnostic is designed to detect leaks as small as 0.51 mm (0.020 in). The diagnostic can determine if a small leak is present based on vacuum or pressure readings in the EVAP system. When the system is sealed, a finite amount of pressure or vacuum will be observed. When a 0.51 mm (0.020 in) leak is present, often little or no pressure or vacuum is observed. If the test reports a failing value, DTC P0442 will set.
Canister Vent Restriction Test
If the evaporative emission (EVAP) vent system is restricted, fuel vapors will not be properly purged from the EVAP canister. The control module tests this by commanding the EVAP purge solenoid valve ON, commanding the EVAP vent solenoid valve OFF, and monitoring the fuel tank pressure (FTP) sensor for an increase in vacuum. If the vacuum increases more than a calibrated value, DTC P0446 will set.
Purge Solenoid Valve Leak Test
If the evaporative emission (EVAP) purge solenoid valve does not seal properly fuel vapors could enter the engine at an undesired time, causing driveability concerns. The control module tests for this by commanding the EVAP purge solenoid valve OFF and the vent solenoid valve ON, sealing the system, and monitors the fuel tank pressure (FTP) for an increase in vacuum. If the control module detects that the EVAP system vacuum increases above a calibrated value, DTC P0496 will set.