Nero Performance · Gaziantep

Gaziantep EGR Fault Solution

EGR system · fault finding · Gaziantep

An EGR fault is usually not one broken part but a system that has filled with soot over time. Below you'll find what the EGR system does, the symptoms of a fault and which measurements we take at Nero Performance.

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What is the EGR system?

EGR is the system that routes part of the exhaust gas back to the intake side. The returned gas lowers the oxygen level and the combustion temperature in the chamber, which reduces the formation of nitrogen oxides (NOx).

The system consists of a valve, on most cars a cooler (EGR cooler), a control circuit and sensors that monitor flow. The control unit decides how far the valve opens according to engine load, speed and temperature, then measures actual flow and compares it with what it asked for.

EGR fault symptoms

The symptoms differ depending on whether the valve is stuck open or stuck closed.

Engine warning light
The most common symptom; it usually arrives together with a flow or position entry.
Rough idle
With the valve stuck open the idle shakes and the engine may stall from time to time.
Loss of pull
Delayed response and power loss, particularly at low revs.
Black smoke from the exhaust
Incomplete combustion caused by excessive recirculation.
Rising fuel consumption
Consumption can climb because combustion efficiency has dropped.
Hard starting when cold
A leaking valve can make things difficult for a cold engine.

What causes an EGR fault?

The gas the EGR carries contains soot and oil vapour. Most faults are the result of that build-up.

Soot build-up
Soot collecting in the valve seat and the passage stops the valve closing fully.
Short-journey use
A usage pattern where the engine never fully warms up speeds up the build-up.
Blocked cooler
When the passages inside the EGR cooler fill up, flow drops; on some cars a coolant leak appears as well.
Electric valve motor
The position motor or the feedback potentiometer can wear out.
Vacuum circuit
On vacuum-operated systems, a hose, modulator or vacuum pump problem.
Wiring and connector
A corroded connector or a broken wire can generate a code even with a healthy valve.

Which parts are checked on an EGR fault?

EGR valve
Mechanical movement, seat sealing and position feedback.
EGR cooler
Flow restriction and sealing.
Intake manifold and passages
Cross-section narrowed by soot.
Mass air flow (MAF) sensor
On most cars EGR flow is calculated from the measured air mass; a drifting MAF will produce an EGR code.
Intake throttle
On some engines EGR flow is achieved by throttling the intake; a sticking flap lowers the flow.
Vacuum or electrical control
Hoses, modulator, connector and wiring integrity.

How do we diagnose an EGR fault?

With EGR the aim is to separate whether the flow really is wrong, and if so whether the cause is mechanical or electrical.

Code and freeze frame
We look at the engine speed, load and temperature at which the entry was recorded.
Requested / actual flow
The EGR rate the control unit asks for is compared with the measured value while the engine runs.
Valve position feedback
We check whether the commanded position and the position the sensor reports agree.
Actuator test
The valve is driven from the tester and its movement and response time observed.
MAF verification
The expected air mass with EGR closed is compared with the measured value.
Mechanical check
If needed the valve is removed and the soot build-up and seat sealing assessed visually.
Verification
Afterwards the code is cleared, a road test is run under the same conditions and the values read again.

How is the solution decided?

There is no single standard procedure for EGR. What gets done is decided by what the measurement shows.

Cleaning
If soot in the valve seat and the passage is restricting flow, cleaning is carried out.
Wiring repair
Where the problem comes from a connector, a wire or a vacuum line, the circuit is repaired rather than the part replaced.
Sensor / actuator replacement
If position feedback or the control circuit measures faulty, the relevant part is renewed.
Cooler repair
Addressed if a flow restriction or a leak is found in the EGR cooler.
Mechanical work
If the valve mechanism is seized or the seat is leaking, mechanical repair is required.
Adaptation
After the work, valve position learning is carried out to the manufacturer's procedure.

At Nero Performance, EGR work runs along the lines of diagnosis, cleaning, repair, part checking and a return to the operating values the manufacturer specifies. We do not carry out work aimed at disabling emissions systems contrary to regulations.