Conditions for Clearing the MIL/DTC

WARNING: This page is about a different car, the 2004 GMC Sierra, 2004 GMC Cab & Chassis Sierra, 2004 Chevrolet Silverado, and 2004 Chevrolet Cab & Chassis Silverado. However, it is still accessible from the selected car via links, so may be relevant.

The control module turns OFF the malfunction indicator lamp (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.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.

DTC P1404

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Schematic Reference: Engine Control Module (ECM) Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Engine Controls?	-	Go to Step 2	Go to Diagnostic System Check - Engine Controls
2	IMPORTANT: Attaching the shop exhaust system to the vehicle may cause false exhaust gas recirculation (EGR) DTCs to set. Turn ON the ignition. Observe the EGR Position parameter with a scan tool. Does the EGR Position parameter read more than the specified value?	1.25 V	Go to Step 4	Go to Step 3
3	Observe the Freeze Frame/Failure Records for this DTC. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition cycle?	-	Go to Step 4	Go to Intermittent Conditions
4	Is DTC P0403, P0405, or P0406 also set?	-	Go to DTC P0403 or DTC P0405 or DTC P0406	Go to Step 5
5	Test for shorted terminals and poor connections at the exhaust gas recirculation (EGR) valve. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 6
6	Disconnect the EGR valve. Turn ON the ignition. Set up the DMM to measure amperage. Connect a test lamp and a DMM in series between the 5-volt reference circuit of the EGR position sensor and the low reference circuit of the EGR position sensor. Measure the amperage and note as "current draw". Remove the DMM and connect the test lamp between the 5-volt reference circuit of the EGR position sensor and the low reference circuit of the EGR position sensor. Connect a DMM in parallel between the low reference circuit of the EGR position sensor and a good ground. Measure the voltage and note as "low reference voltage drop". Divide the "low reference voltage drop" by the "current draw" in order to calculate the resistance in the low reference circuit. Is the calculated resistance more than the specified value?	5 ohm	Go to Step 7	Go to Step 9
7	Test for shorted terminals and poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections andConnector Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 8
8	Disconnect the engine control module (ECM). Repair the high resistance in the low reference circuit. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	-	Go to Step 12	Go to Step 11
9	Remove the EGR valve. Refer to Exhaust Gas Recirculation (EGR) Valve Replacement . Inspect for debris and damage that will cause the EGR valve to stick and clean, if necessary. Refer to Exhaust Gas Recirculation (EGR) System Cleaning . Did you find and correct the condition?	-	Go to Step 12	Go to Step 10
10	Replace the EGR valve. Refer to Exhaust Gas Recirculation (EGR) Valve Replacement . Did you complete the replacement?	-	Go to Step 12	-
11	Replace the ECM. Refer to Engine Control Module (ECM) Replacement . Did you complete the replacement?	-	Go to Step 12	-
12	Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Start the engine. Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?	-	Go to Step 2	Go to Step 13
13	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	-	Go to Diagnostic Trouble Code (DTC) List	System OK