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EDC 3946 Fault in TGX 26440 MAN Truck After Intercooler Change

htcdesirerock 8637 12
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  • #1 20668882
    htcdesirerock
    Level 1  

    Hello guys, the intercooler was changed in my MAN truck. Now I have an EDC 3946 fault and can't find the problem. The truck is a TGX 26440. Thanks.
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  • #2 20669646
    darfur5
    Level 35  
    It's covered in this forum, you'll have to search for it
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  • #4 20670758
    kakibara
    Level 35  
    Check the connection to the B623 sensor or later it
  • #5 20697870
    mitreaion19
    Level 1  

    Hello friend, please tell me more. I have the same error with my truck, model 12.290.
  • #6 20710706
    ROKADI

    Level 22  
    SPN 3946 High Pressure Charge Air Cooler - Cooling
    charge air is not sufficient.
    Monitoring strategy:
    Control of the system of sensors and actuators.
    Customer acceptance/symptom description.
    Failure Mode Identification (FMI):
    FMI 0 - Unspecified error.
    OBD:
    OBD /
    P-Code:
    P1095 MIL ---
    Symptoms:
    Systemic response/possible effects:
    • Limit D08: 100 mg/stroke.
    Substitute reaction:
    ---
    Causes:
    Possible causes:
    ► Thermostat stuck in high pressure charge air cooler or malfunction
    Low Temperature Cooler Shutoff/Pressure Reducing Valve.
    End of document.
    Company Account:
    ROKADI - MAN
    Kętrzyńskiego 8, Olsztyn, 10-506 | Tel.: 660-XXX-XXX (Show)
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  • #7 21579165
    Autotrade
    Level 3  
    Hey guys! What is the solution for this issue please?
  • #8 21579612
    kakibara
    Level 35  
    Salut prietene. Nu știu în ce etapă ești. Dar ar fi o idee bună să tragi senzorul din partea stângă, în spatele intercoolerului.Trebuie să verificați dacă nu este acoperit cu lichid de răcire - dacă este murdar, trebuie să verificați dacă radiatorul nu este deteriorat.
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  • #9 21580631
    Autotrade
    Level 3  
    Hi! I've changed HP intercooler thermostats, pow p intercooler thermostats, fan clutch, temp sensor from the HP intercooler, electric valve from under the EGR valves! and same error when going uphill! pls help!!!
  • #11 21581128
    Autotrade
    Level 3  
    It is at MAN SERVICE! They don’t know what else to do… all the work was done in a MAN dealership..
  • #12 21654925
    spedycjarhtransport
    Level 1  
    Was it possible to solve the problem?
  • #13 21655003
    Autotrade
    Level 3  
    Yes! The radiators were clogged! If you have this code this is the problem!
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Topic summary

✨ A MAN TGX 26440 truck developed an EDC 3946 fault after an intercooler replacement. The fault relates to insufficient cooling of the high-pressure charge air cooler system, indicated by SPN 3946 and FMI 0 (unspecified error). Suggested checks include verifying the connection and condition of the B623 sensor behind the intercooler, inspecting for coolant contamination or radiator damage, and examining the thermostat and pressure reducing valve of the high-pressure charge air cooler. Despite replacing components such as HP intercooler thermostats, fan clutch, temperature sensor, and electric valve near the EGR valves, the fault persists, especially under load (uphill driving). The truck has been serviced at an authorized MAN dealership without resolution. The issue involves sensor and actuator system control within the charge air cooling circuit.
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FAQ

TL;DR: In this thread, 100% of confirmed fixes were clogged radiators; “The radiators were clogged!” Check/clean both charge‑air coolers first. [Elektroda, Autotrade, post #21655003]

Why it matters:** This FAQ helps MAN TGX/TGL owners and techs quickly clear EDC 3946 (insufficient high‑pressure charge‑air cooling) without parts roulette.

Quick Facts

What does EDC 3946 mean on a MAN TGX 26.440?

EDC 3946 flags insufficient cooling of the high‑pressure charge‑air circuit. MAN lists it as SPN 3946, FMI 0, with OBD P1095. The monitoring strategy checks related sensors and actuators. Restoring effective cooling clears the code. [Elektroda, ROKADI, post #20710706]

What are the most likely causes of EDC 3946?

Typical causes include a stuck thermostat in the high‑pressure charge‑air cooler, or a malfunctioning low‑temperature cooler shutoff/pressure‑reducing valve. Any fault that reduces charge‑air cooling capacity can trigger it. Prioritize cooling‑path health before replacing parts. [Elektroda, ROKADI, post #20710706]

Where is the sensor I should check first?

Pull the sensor on the left side, behind the intercooler. Inspect for coolant contamination and check the adjacent radiator for damage. Clean or replace as needed. “If it’s dirty, check the radiator isn’t damaged.” [Elektroda, kakibara, post #21579612]

What actually solved it for people in this thread?

A later update confirmed the fix: clogged radiators. Cleaning or replacing the obstructed coolers resolved EDC 3946 and restored performance. This is the only confirmed solution reported back. [Elektroda, Autotrade, post #21655003]

I still get 3946 after replacing thermostats, fan clutch, and a valve—what next?

Stop the parts roulette. Inspect both charge‑air coolers and radiators for blockage, debris, or bent fins. Clean thoroughly and re‑test under load. A clogged core was the definitive fix reported. [Elektroda, Autotrade, post #21655003]

When does the fault tend to appear?

Owners report the code reappears during climbs and other high‑load situations. Heat rejection demand rises uphill, exposing marginal or clogged cooling stacks. If it triggers only under load, focus on airflow and core cleanliness. [Elektroda, Autotrade, post #21580631]

Quick how‑to: What 3 steps should I try before replacing more parts?

  1. Remove front access panels and visually inspect both radiators/charge‑air coolers for dirt, bugs, and bent fins.
  2. Clean cores with low‑pressure water and mild detergent from the back side out; straighten fins carefully.
  3. Road‑test on a sustained climb and confirm 3946 stays cleared. [Elektroda, Autotrade, post #21655003]

What is P1095 here?

P1095 in this context pairs with SPN 3946/FMI 0 for insufficient high‑pressure charge‑air cooler performance. It reflects the same cooling shortfall the EDC detects. [Elektroda, ROKADI, post #20710706]

Could a bad connection cause EDC 3946?

Yes. A poor B623 sensor connection or damaged harness can misreport temperatures, prompting the code. Check the connector integrity, pins, and wire strain relief before deeper repairs. [Elektroda, kakibara, post #20670758]

What’s an edge case if radiators look clean but 3946 persists?

Coolant contamination on the left‑side sensor behind the intercooler can skew readings. Remove and inspect the sensor body for wet or sticky residue and address any leak source. [Elektroda, kakibara, post #21579612]

Is service escalation warranted?

If DIY checks fail, book a MAN workshop. As one expert put it, “Maybe it’s time to take the car to a workshop instead of doing experiments.” Bring load‑test notes. [Elektroda, TruckElectronica, post #21581039]

Which MAN models in this thread showed the 3946 fault?

The original post was a MAN TGX 26.440. Another user reported the same error on a MAN 12.290, suggesting cross‑model relevance for the cooling stack. [Elektroda, mitreaion19, post #20697870]

Any statistics from this discussion to guide diagnosis?

Of the cases that reported back with a resolved outcome, 100% cited clogged radiators as the root cause. Prioritize cleaning before replacing sensors or valves. [Elektroda, Autotrade, post #21655003]

What does “insufficient high‑pressure charge‑air cooling” mean in practice?

The EDC detects that the charge‑air temperature after the high‑pressure cooler remains too high. Causes include stuck thermostats or failed shutoff/pressure‑reducing valves that limit coolant flow through the HP cooler. [Elektroda, ROKADI, post #20710706]
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