Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
EGR Vacuum Regulator Solenoid Valve With Potentiometer, Checking
Observe all safety precautions: SAFETY PRECAUTIONS
View clean working conditions: CLEAN WORKING CONDITIONS
Perform a preliminary check to verify the condition: PRELIMINARY CHECK .
Use only gold-plated terminals when servicing any component with gold-plated electrical harness connector terminals.
See Appropriate Wiring Diagram Information for component locations and connector views.
The EGR Vacuum Regulator Solenoid Valve and High Pressure EGR Valve both refer to the same component N18 or V338. Name changes occur in Appropriate Wiring Diagrams, parts listings etc. The EGR potentiometer G212 is part of the N18 or V338 valve assembly and is serviced as one component.
Special Tools And Workshop Equipment Required
- Multimeter
- Electrical connector test lead set
Test Conditions
- Fuse OK
- Battery voltage 12.5 V
- Ignition switched off
Start Diagnosis
-- Disconnect the EGR/Potentiometer -N18/V338 - electrical harness connector. Refer to Appropriate Wiring Diagrams for Pin locations.
Checking Internal Resistance
-- Using a multimeter, check the EGR/Potentiometer -N18/V338 - terminals 2 to 6 for resistance.
Specified Value: 18.5 Ω (+/- 1.3 Ohms).
-- Using a multimeter, check the EGR/Potentiometer -N18/V338 - terminals 1 to 5 for resistance.
Specified Value: 175.6 Ω (+/- 20 Ohms).
If Any Of The Specified Values Are Not Obtained:
-- Replace the EGR/Potentiometer -N18/V338 -.
If The Specifications Were Obtained:
Checking Voltage
-- Switch the ignition On.
-- Using a multimeter, check the EGR/Potentiometer -N18/V338 - electrical harness connector terminal 2 to Ground for voltage.
-- Using a multimeter, check the EGR/Potentiometer -N18/V338 - electrical harness connector terminal 6 to Ground for voltage.
-- Using a multimeter, check the EGR/Potentiometer -N18/V338 - electrical harness connector terminal 3 to Battery Positive (+) for voltage.
Specified Value For Above Tests: Near Battery Voltage.
-- Using a multimeter, check the EGR/Potentiometer -N18/V338 - electrical harness connector terminal 1 to Ground for voltage.
-- Switch the ignition Off.
Specified Value: Near 5.01 V
If Any Of The Specified Values Were Not Obtained:
-- Check the EGR/Potentiometer -N18/V338 - electrical harness to the Motronic Engine Control Module (ECM) -J623- for an for an open circuit or a short circuit. Refer to Appropriate Wiring Diagrams for Pin locations.
-- Check the wiring connections for damage, corrosion, loose or broken terminals.
-- If necessary, repair the faulty wiring connection.
If The Specified Value Was Obtained:
Checking wiring
-- Remove the Motronic Engine Control Module (ECM) -J623-.
-- Using a multimeter, check the EGR/Potentiometer -N18/V338 - electrical harness connector terminal to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T60 terminal for resistance. Refer to Appropriate Wiring Diagrams for Pin locations.
| EGR/Potentiometer -N18/V338 - electrical harness connector terminal | Motronic Engine Control Module (ECM) -J623- electrical harness connector T60 terminals |
|---|---|
| 1 | 25 |
| 2 | 4 |
| 3 | 53 |
| 5 | 57 |
| 6 | 19 |
Specified Value: 1.5 Ω Max.
If The Specification Was Not Obtained:
-- Check the wiring for high resistance, a short circuit to each other, Battery or Ground.
-- If necessary, repair the faulty wiring connection.
-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.
If No Malfunction Is Detected In The Wiring And The Voltage Was Not Ok:
-- Replace the Motronic Engine Control Module (ECM) -J623-.
Final Procedures
After the repair work, the following work steps must be performed in the following sequence:
- Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
- If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
- If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.