EGR System Flow Too Low (NTC)
FH. Diagnostic trouble code (DTC) 2-4-1 DI EZ 116 K (NTC)
* 2-4-1 EGR system flow too low (NTC)
EGR Systems with NTC type temperature sensors
Chassis numbers for EGR systems with NTC sensors
The following table shows the chassis numbers of the cars in which NTC type EGR sensors were installed at the factory. The chassis numbers are divided into car models and place of manufacture. Cars with lower chassis numbers have had PTC type EGR sensors installed.
For EGR systems with PTC temperature sensors see section FJ. EGR System Flow Too Low (PTC)
DTC conditions:
- Warm engine (above 65°C (149°F)), engine at part loads and the EGR signal does not change.
When the control module sends a control signal to the EGR vacuum controller the signal from the EGR temperature sensor should change. If it does not do so the control module interprets this as a flow fault and logs the DTC
Causes of fault:
- Break in the signal wiring
- No voltage to the EGR vacuum controller
- Faulty EGR vacuum controller
- Poor vacuum to the EGR valve (In the white hose)
- Defective yellow hose (spilt, clogged)
- Faulty EGR valve (does not open)
- Faulty temperature sensor
Note: Be careful when removing yellow and white hoses. The hoses may burst or crack if they are removed roughly from nipples.
FH1
Check that the EGR vacuum controller Is working
- Start and warm up the engine.
Place your hand on the EGR vacuum controller and rev the engine (over 2000 rpm) several times. The vacuum controller should tick.
If the EGR vacuum controller ticks (is operating)
^ check the vacuum to the EGR vacuum controller FH2.
If the EGR vacuum controller does not tick (not operating)
^ check the voltage to the EGR controller FH5.
FH2
Checking the vacuum to the EGR vacuum controller
- Engine running
Carefully remove the white hose from the EGR vacuum controller and check to see if there is a vacuum in the hose.
If there is no vacuum
^ check the white hose between the EGR vacuum controller and the intake manifold. The hose should not leak or be clogged. Replace the hose if necessary.
If there is a vacuum
^ check the vacuum from the EGR vacuum controller FH3.
FH3
Checking the vacuum from the EGR vacuum controller
- Engine running.
- Connect the white hose to the EGR vacuum controller.
- Carefully remove yellow hose from the controller.
- Connect a pressure gauge to the controller nipple.
Rev the engine. Check that the controller is not losing the vacuum. The pressure gauge needle should oscillate rapidly.
If the pressure gauge needle does not oscillate
^ try using a new EGR vacuum controller.
If the pressure gauge needle oscillates
^ check the EGR valve FH4
FH4
Checking the EGR valve
- Engine running.
- Connect a vacuum pump to the yellow hose at the EGR vacuum controller.
Pump up a vacuum (max. 30 kPa=4.3psi). Check that the EGR valve moves and is holding the vacuum. The engine should idle unevenly when the valve is open.
There are three possibilities, as follows:
If the valve does not open:
^ Check to see if the yellow hose is clogged. If the hose is OK, try using a new EGR valve.
If the valve opens but loses vacuum:
^ Check the yellow hose for leaks. If the hose is OK, try using a new EGR valve.
If the valve opens and holds a vacuum, but the engine idles evenly:
^ The EGR pipes are clogged. Clean the pipes.
FH5
Checking the voltage to the EGR controller
- Switch off the engine.
- Ignition on.
- Disconnect the connector.
Connect a voltmeter between terminal 2 in the EGR vacuum controller wiring connector and GND.
The voltmeter should read battery voltage.
If this value is OK:
^ Check the signal wiring FH6.
If the reading is incorrect (no voltage):
^ Check the wiring between terminal 2 on the EGR vacuum controller and the ignition switch for breaks in accordance with NA2. NA. Checking the Wiring
FH6
Checking the signal wiring
- Ignition on.
- Connector disconnected.
Connect a voltmeter between terminals 1 and 2 in the EGR vacuum controller wiring connector. The voltmeter should read 0 V.
If the voltmeter reads 0 V
^ check the signal FH7.
If voltmeter made battery voltage
^ check the wiring for grounding in accordance with NA3. NA. Checking the Wiring
FH7
Checking the signal
- Start the engine.
- Connect the voltmeter between terminals 1 and 2 in the EGR vacuum controller wiring connector.
Check the voltmeter while revving the engine. The voltmeter should register a voltage for a moment before returning to 0 V.
If the voltmeter registers a voltage
^ try using a new EGR vacuum controller.
If the voltmeter does not register a voltage
^ check the wiring between terminal 1 on the controller connector and terminal 15 on the control module for breaks in accordance with NA2. NA. Checking the Wiring
If this wiring is OK: Check the wiring between the GND terminal (at the intake manifold) and terminal 14 on the control module as well.