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
- Code map: SPN 3946, FMI 0; OBD P1095; symptom is insufficient high‑pressure charge‑air cooling. [Elektroda, ROKADI, post #20710706]
- Real‑world trigger: fault repeats under uphill load even after multiple parts replaced. [Elektroda, Autotrade, post #21580631]
- Fast check: inspect left‑side sensor behind intercooler for coolant contamination and radiator damage. [Elektroda, kakibara, post #21579612]
- Proven fix in thread: wash/unclog or replace obstructed radiators/charge‑air coolers. [Elektroda, Autotrade, post #21655003]
- Wiring sanity: verify B623 sensor connection and harness before deeper teardown. [Elektroda, kakibara, post #20670758]
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?
- Remove front access panels and visually inspect both radiators/charge‑air coolers for dirt, bugs, and bent fins.
- Clean cores with low‑pressure water and mild detergent from the back side out; straighten fins carefully.
- 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]
