Diagnostic Trouble Code (DTC) P1404

Exhaust Gas Recirculation Closed Valve Pintle Error

 

 

 

Features of the Circuit

 

 

  • Oxides of Nitrogen (NOx) emission levels resulting due to high combustion temperatures are lowered with the help of the Exhaust Gas Recirculation (EGR) system.
  • The required result is achieved by supplying trace amounts of exhaust gases back into the combustion chamber.
  • Combustion temperatures are automatically reduced if the exhaust gases dilute the air/fuel mixture.
  • The linear EGR valve which is used in the system has been modeled to provide exhaust gases to the engine correctly, as needed without using the intake manifold vacuum.
  • The exhaust flow going into the intake manifold from the exhaust manifold through an orifice with an ECM controlled pintle is controlled by the valve.
  • The ECM is able to regulate the pintle position taking inputs from the Throttle Position (TP) and Manifold Absolute Pressure (MAP) sensors.
  • After obtaining these inputs the ECM signals the EGR valve to start working if necessary.
  • This is done by controlling an ignition signal through the ECM.
  • A Scan tool can be used to oversee the Desired EGR Position.
  • The ECM uses a feedback signal to control the results of its command.
  • A voltage signal representing the EGR valve pintle position is sent to the ECM by transmitting a 5 volt reference and a ground to the EGR valve.
  • This feedback signal which is the actual position of the EGR pintle can also be overseen on a scan tool.
  •  It must be noted that the Actual EGR Position must always revolve round the commanded or Desired EGR Position.

 

 

 

 

 

When will DTC set?

 

Task boosted after DTC sets

When will DTC clear?

DTC sets when

1) Engine keeps running.

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1) The Malfunction Indicator Lamp (MIL) will be seen to illuminate, after three consecutively failed trips.

1) The MIL will go off after three successive ignition cycles in which the diagnostic runs faultlessly.

 

2) Difference between current and learned low position > 6.29%.

 

 

2) The ECM will begin to record operating conditions when the diagnostic fails.

 

2) A history DTC will clear after 80 consecutive warm-up cycles without a fault.

3) Desired EGR position = 0.

 

3) This data will be stored in the Freeze Frame and Failure Records will be boosted.

 

3) A Scan Tool can be used to unset all DTCs.

4) Ignition voltage dwells round 11 and 15.8 volts (SOHC).

 

4) A history DTC is stored.

4)  De-linking the ECM battery feed for more than 10 seconds

5) Ignition voltage dwells round 11.7 and 16 volts (DOHC).

 

5) EGR is disabled.

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6) Airfuel ratio > 14.5.

 

 

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7) Intake Air Temperature (IAT) stays round 3°C (37.4°F) and 120°C (248°F).

 

 

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8) Startup Engine Coolant Temperature (ECT) > 10°C (50°F).

 

 

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9) Engine Coolant Temperature (ECT) > 65°C (149°F).

 

 

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10) DTCs P0112, P0113, P0405, P0406, and P0502 are not set.

 

 

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Assistance in Diagnostics

 

  • The EGR valve may be seen to freeze and stick in cold weather if there is moisture associated with exhaust systems.
  • The valve will become warm and the problem disappear if the vehicle is taken into a warm shop for repairs.
  • On observing the Actual EGR and the Desired EGR Positions with a Scan Tool on a cold vehicle the problem may be verified.
  •  In that case you need to examine the freeze frame data to note if the DTC was set when the vehicle was cold.
  • This can be done by noting the Engine Coolant Temperature (ECT).

 

 

 

 

Purpose of the test

 

 

Number(s) below indicate the step number(s) to be followed on the Diagnostic Table.

 

 

1.The On-Board Diagnostic (EOBD) System Check assists the technician to undertake some elementary check ups and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the information taken when the malfunction occurred. The information is then stored on the scan tool for future reference.

 

 

2.Whether the EGR system can control the EGR valve correctly and whether the fault is present can be learned by controlling the EGR valve open.

 

3.The Scan Tool will show the actual EGR Position as 0% when the EGR valve electrical connector is de-linked. In case it does not happen likewise then the error is either in the EGR signal circuit or the ECM.

 

 

5.The Digital Voltmeter (DVM) will read battery voltage, additional DTCs may set and engine performance too will deteriorate if the ERG valve 5 volt reference is shorted to voltage.

 

 

6.The change of the ECM must be reprogrammed. You may consult the latest Techline procedure for ECM reprogramming.

 

 

10.   An open or poor connection condition may have caused this DTC to set. Be sure to examine the terminals and see if they are being backed out, inaccurately formed or tampered or if there is unimpressive tension.

 

 

11.   It must be noted that all circuits to the EGR valve remain okay at this point. The error is internal in the EGR valve and hence it needs to be changed. Ensure that all gasket material is taken away from the EGR mounting surface. You must note that even a small amount of material may initiate a DTC P0401.

 

 

12.   Examine if the terminals are backed out, inaccurately formed or tampered and also if any unimpressive tension prevails.

 

 

13.   Unsetting all DTCs is a vital step for this diagnostic. The clearing function enables the EGR valve to relearn a new pintle position as the former pintle position was incorrect because of the failure that was responsible for setting the DTC. The DTC must be unset letting the ignition remain ON while the engine is OFF or when the engine is at idle. The new pintle will not be known if the ECM gets an EGR command.

 

 

14.   You need to consult "Diagnostic Aids" in this section for further checks and data in case no malfunctions were found at this point and no additional DTCs set.