Good morning.
The 420 has nothing to do with back pressure. It has to do with processing the gases from the exhaust. The precious metals inside are worn out. It needs to be replaced whether it has the 410 or not.
As far as the 410, do you hear the pump coming on at cold start?
Circuit description:
An air pump is used on this vehicle in order to lower the tail pipe emissions on start-up. The power-train control module (PCM) grounds the air pump relay control circuit, which energizes the air pump. The PCM also grounds the air combination valve vacuum control circuit, which energizes the air vacuum solenoid valve. Vacuum is then applied to both air combination valve diaphragms which open the shut-off valves. The PCM enables both circuits simultaneously when air system operation is desired.
When the air system is active, the air pump forces fresh air into the exhaust stream in order to accelerate catalyst operation. The air solenoid valves replace the conventional check valves. When the air system is inactive the shut-off valves prevent air flow in either direction. DTC P0412 applies to the air vacuum control solenoid circuit. DTC P0418 applies to the AIR pump relay control circuit. DTC P0410 sets if an air flow problem is detected.
The PCM will run up to three diagnostic tests using the HO2S one voltage to diagnose the air system. The first is a passive test, it has two parts. The two parts are the air passive test one, and air passive test two. The second test is an active test, it has one part. This test is named air active test.
The air passive/active tests consist of the following:
air passive test one:
When the air system is enabled, the PCM monitors the HO2S one voltage for a specific amount of time calculated by the coolant temperature at start-up. The HO2S one is monitored for ten seconds if the coolant temperature is more than 90°C (194°F), or 70 seconds if the coolant temperature is less than 90°C (194°F).
If the HO2S one voltage goes below a calibrated amount, the PCM interprets this as an indication the air system is operational and it is considered a test passed.
When the air passive test one completes, the PCM then runs the air passive test two.
Air passive test two:
When the air system is disabled, the PCM monitors the HO2S one voltage. The HO2S one voltage should increase above a calibrated amount and switch normally.
When the air passive test two is complete and both air passive tests indicate a pass, no further action is taken. If either one of the above tests have failed or is inconclusive, the diagnostic will proceed to the air active test.
Air active Test
During this test the PCM turns the air system on during closed loop operation. When the air system is activated, the PCM monitors the HO2S voltage. If the air system is operating properly, the HO2S one voltage should go below a predetermined level.
The PCM will repeat this test up to three consecutive times with a short delay between each command.
If the PCM determines that the HO2S one voltage did not respond as expected during the tests, DTC P0410 will set.
Conditions for running the DTC:
DTCs P0101, P0102, P0103, P0107, P0108, P0112, P0113, P0117, P0118, P0121, P0122, P0123, P0171, P0172, P0300, P0412, P0418, P0442, P0443, P1441, and HO2S are not set.
The engine operates for more than two seconds.
Condition for not passing air active test:
The HO2S one voltage changes less than 0.06 or is more than 225 mV for 1.5 seconds during 2.5 seconds of air pump operation.
Conditions for setting the DTC;
The pre-catalyst HO2S voltage remains above 300 mV (passive) or 150 mV (active) for a calibrated period of time.
And
The short term FT does not increase a calibrated amount during the test.
Both the above conditions exist for three consecutive tests.
Acattion taken when the DTC sets:
The PCM will illuminate the malfunction indicator lamp (MIL) during the second consecutive trip in which the diagnostic test has been run and failed.
The PCM will store conditions which were present when the DTC set as freeze frame and failure records data.
If the misfire is determined to be catalyst damaging, the PCM will flash the MIL.
Conditions for clearing MIL/DTC:
The PCM will turn OFF the MIL during the third consecutive trip in which the diagnostic has been run and passed.
The History DTC will clear after forty consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using a scan tool.
Diagnostic aids:
Inspect for the following:
Important: Remove any debris from the connector surfaces before servicing a component. Inspect the connector gaskets when diagnosing or replacing a component. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion.
Faulty terminal connection - Inspect the harness connectors for the following conditions:
- Backed out terminals.
- Improper mating.
- Broken locks.
- Improperly formed or damaged terminals.
- Faulty terminal to wire connection- Use a corresponding mating terminal to test for proper tension. Refer to testing for intermittent and poor connections and connector repairs in diagrams.
Damaged harness - Inspect the wiring harness for damage.
If the harness inspection does not reveal a problem, observe the display on the scan tool while moving connectors and wiring harnesses related to the sensor. A change in the scan tool display may indicate the location of the fault. Refer to circuit testing and wiring repairs in diagrams.
Clean and secure connections at the PCM and the engine grounds.
If the DTC is determined to be intermittent, reviewing the failure records can be useful in determining when the DTC was last set.
Test description:
The numbers below refer to the step numbers on the diagnostic table:
2. DTC P0412 air solenoid valve control circuit and P0418 air pump relay control circuit should be diagnosed first if either are set.
3. This step begins testing for a short to ground in the air pump feed circuit.
4. Listen for a running motor, command both the "on" and "off" states. Repeat the commands as necessary.
5. This step begins testing for a short to voltage in the pump feed circuit.
6. This step tests for voltage at the air pump relay switch feed circuit.
7. This step bypasses the relay.
9. This step tests for voltage on the air pump feed circuit.
10. This step tests for an open on the pump ground circuit.
29. The air pump is not designed to run continuously. If the pump needs to be replaced, inspect for conditions that may cause continuous pump operation.
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Monday, April 2nd, 2018 AT 4:03 AM
