Renault Trafic M9r error P0100 and P0409

Cristiano,

Your voltage list is actually very useful. The important clue is this:

You have P0100 and P0409 at the same time, and both systems use the ECU’s 5 V reference / sensor ground / signal monitoring.
P0100 is a MAF circuit fault, and P0409 is an EGR position/sensor circuit fault, not simply “dirty EGR.”

What looks normal

MAP sensor connector

With the MAP disconnected, this looks normal:

So the MAP circuit itself is probably not the cause, especially since you already replaced the MAP sensor.

MAF connector

Your MAF values also look mostly logical:

A MAF with 12 V supply, 5 V reference and grounds present does not prove the MAF is good, but it means the connector is not obviously dead.

The suspicious part: EGR connector

Your EGR readings:

The key one is EGR P5 = 1.22 V with the EGR disconnected.

On many Renault/Vivaro/Trafic M9R EGR systems, the EGR has a motor plus an internal position sensor. P0409 relates to the EGR position/sensor circuit, and Renault/Trafic owners have reported this exact type of P0409 as an EGR sensor circuit issue rather than only a dirty valve.

With the valve unplugged, the EGR position signal should usually be either pulled up near 5 V, pulled down near 0 V, or show a clearly defined ECU bias voltage depending on ECU design. 1.22 V is not automatically impossible, but it is suspicious if the ECU interprets it as an invalid EGR position signal.

My strongest suspicion

I would not replace the MAP again. I would focus on one of these:

1. EGR position signal wire problem
2. EGR internal position sensor fault despite the valve “testing” mechanically
3. shared 5 V / sensor ground disturbance when components are plugged in
4. MAF signal plausibility fault caused by EGR/throttle air-flow mismatch
5. less likely: ECU input fault

P0100 and P0409 together can happen because the ECU compares MAF air flow, MAP pressure, throttle flap position and EGR position. If the ECU commands EGR movement but the EGR feedback is wrong, the measured air mass may not match expectation, so a MAF circuit/range fault can be triggered even when the MAF wiring looks okay.

Do these tests next

1. Test with sensors plugged in, not only disconnected

Your current measurements are with sensors disconnected. That checks supply, but not loaded operation.

Back-probe with everything connected, ignition ON:

EGR position signal
Find which pin changes when the EGR is commanded with diagnostic tool. The signal should move smoothly, usually somewhere inside roughly 0.5–4.5 V, not jump, drop out, or stay fixed.

MAF signal
With engine idling, the MAF signal or live-data air mass must be plausible and stable. If MAF live data is frozen, zero, maximum, or jumps wildly, then P0100 becomes more direct.

2. Unplug EGR, clear codes, start engine, see what returns first

Do this as a diagnostic test only:

1. unplug EGR
2. clear all codes
3. ignition off/on
4. start engine
5. read codes immediately

Expected result: you may get an EGR open-circuit type fault.
Important question: does P0100 return immediately too?

If P0100 disappears or changes when EGR is unplugged, the EGR or its wiring is probably dragging down or corrupting a shared sensor line. There are similar cases on Trafic/Vivaro platforms where a bad EGR affected the 5 V reference and caused air-flow related faults.

3. Check voltage drop on sensor ground

Do not only check continuity with an ohmmeter. Do a voltage-drop test.

Ignition ON, sensors connected:

• multimeter positive to battery negative
• multimeter negative to MAP/MAF/EGR sensor ground pin

You want very close to 0.00 V.
If you see for example 0.1–0.5 V, the sensor ground is bad even if continuity “seems okay.”

Also test with engine running and while wiggling the loom.

4. Wiggle-test the loom near EGR/MAF/throttle

On the Trafic/Vivaro/Primastar M9R, the loom around the EGR/throttle/intake area gets heat, oil mist and vibration. Look especially for:

• rubbed insulation near the EGR cooler/intake pipe
• oil inside connector plugs
• spread female terminals
• green corrosion
• broken wire inside insulation near the connector strain relief
• poor ECU connector pins

A wire can show continuity with a meter but fail under vibration or load.

5. Compare EGR command vs EGR feedback with live data

With CLIP, Delphi, Autel, Launch, etc., look at:

• EGR command %
• EGR actual position %
• MAF kg/h or mg/stroke
• MAP pressure
• throttle flap command / position

At ignition ON engine OFF, EGR command and feedback should be believable and not stuck at an impossible value.

At idle:

• command EGR open/closed with actuator test if possible
• MAF should change when EGR opens/closes
• EGR feedback should follow command

If command changes but feedback stays fixed, P0409 is justified.

About the throttle body voltages

Your throttle body connector has several 4–5 V readings:

That does not immediately look wrong with the unit disconnected. The throttle flap on these engines is used for EGR control and shutdown, so if the throttle position feedback is wrong, it can also disturb EGR/MAF plausibility. But because your stored codes are P0100 + P0409, I would check EGR feedback first.

Most likely repair path

My order would be:

1. Back-probe EGR position signal connected.
2. Check sensor ground voltage drop under load.
3. Check whether EGR P5 changes smoothly during actuator command.
4. If P5 is stuck around 1.2 V or jumps: repair EGR signal wire or replace EGR valve with a known-good/OE-quality unit.
5. If EGR feedback is perfect, then test MAF live data and MAF signal under running conditions.
6. Only suspect ECU after proving 5 V, ground, signal wire continuity and loaded signal behavior at the ECU pins.

My practical bet from your numbers: the fault is around the EGR position feedback circuit, especially the P5 line, and P0100 is probably a consequence of air-flow plausibility rather than the original fault.

Greetz Micha