3100 Fault Code: Boost Pressure Control Deactivated (BMW Repair Guide)
3100 is a BMW-specific code meaning the DME switched off boost pressure control. It is not a fault in itself but the consequence of another fault — so the real job is finding the primary code that triggered it.
— Tekin Code
3100 is a code from BMW's hex fault code system, stored by the DME, and it means "boost pressure control deactivated". It differs from most codes in one important way: 3100 does not describe a failure, it describes a decision the DME made. The system detected an unreliable condition somewhere else, switched boost control off and moved the car to the safe side. That is why trying to "repair" 3100 on its own is wasted effort — the job is to find the primary fault that triggered it.
What Does 3100 Mean?
The DME manages charge pressure as a closed loop: it calculates a target, applies it through the wastegate or VTG actuator, reads the result from the pressure sensor and corrects. If any link in that loop becomes unreliable — an implausible sensor signal, an actuator that does not respond to commands, or a target that can never be reached — the DME opens the loop. Control is deactivated, boost is limited, and 3100 is stored.
In practice 3100 is almost always the last link in a chain. The codes that accompany it most often are 2C57 (pressure too low), 30FE (overboost) and 2ABC (pressure sensor electrical). If you see 3100 alone in the fault memory, the primary code has most likely been cleared or has not become permanent yet — you need driving data to find it.
Code .............. 3100
Definition ........ Boost pressure control deactivated
Module ............ DME (Engine Control Unit)
Type .............. Secondary / consequence code
Typical primary --- 2C57 (pressure too low), 30FE (overboost),
codes ............. 2ABC (sensor electrical), actuator and vacuum codes
Severity .......... Moderate - power loss, limp mode
Common engines .... N54, N55, N20/N26, N63, B48/B58 and diesel equivalents
Symptoms
• Clear loss of power; it no longer feels like the turbo is coming on.
• Limp mode and Check Engine light; some cars also show a "Drivetrain" warning.
• Loss of top-end pull, with flat acceleration especially above 3000 RPM.
• Briefly returning to normal after a restart, then losing power again.
• Higher fuel consumption and delayed throttle response.
• The code rarely appearing alone — usually alongside a boost-related code.
Possible Causes
The list below is not the cause of 3100, but of the primary fault that triggers it — and that is exactly what you are looking for during diagnosis.
• Charge air leak: cracked charge pipe, loose clamp, split coupler (usually alongside 2C57).
• Seized wastegate or VTG mechanism — this can produce both low-pressure and overboost scenarios.
• Failed boost control solenoid, or a disconnected/cracked vacuum hose.
• Drifted charge pressure sensor (TMAP), corroded connector, broken wiring.
• Implausible ambient pressure sensor or IAT value, corrupting the DME's calculation.
• Exhaust restriction (catalyst, DPF) making the target unreachable.
• Mechanical turbocharger failure — shaft play, wheel damage.
• Mismatched software or a badly installed aftermarket boost controller.
• Low supply voltage / weak battery, upsetting actuator and sensor behaviour.
Diagnostic Steps with OBDThink
The method for 3100 is different: you look at the code history, not at parts. Your goal is to find out why the DME switched control off.
• 1. Scan all modules and list the codes one by one. Which boost code sits next to 3100 — 2C57, 30FE or 2ABC? The answer decides your diagnostic path.
• 2. Compare the frequency counters and last-occurrence data. If the primary code repeats more often than 3100, that is your root cause.
• 3. Read the freeze frame: at what RPM, load and temperature was 3100 stored? Full throttle points to mechanics or a leak; low load points to the sensor side.
• 4. With the ignition on and the engine off, validate the charge pressure sensor: it should read ~1.00 bar. Any deviation makes the sensor your primary fault.
• 5. Watch target and actual boost live. With control deactivated the actual value never follows the target — that is expected behaviour, not the problem itself.
• 6. Check whether the wastegate duty cycle responds to commands; with control disabled it may simply stay fixed.
• 7. Clear the fault memory and take a controlled drive. Which code returns first points straight to the root cause — this is the single most valuable step in diagnosing 3100.
• 8. After fixing the primary code, confirm that 3100 disappears on its own.
Reading the code chain
Scenario A:
2C57 (12 times) + 3100 (3 times) -> root cause: low pressure (leak/wastegate)
Scenario B:
30FE (8 times) + 3100 (2 times) -> root cause: overboost (wastegate won't open)
Scenario C:
2ABC (21 times) + 3100 (5 times) -> root cause: sensor/wiring
Scenario D:
3100 only -> primary code was cleared; clear and drive again
Check values:
Sensor (key-on) ........ ~1.00 bar
Boost target/actual .... deviation < 0.15 bar while control is active
Battery (running) ...... 13.8 - 14.6 V
Clearing the fault memory with OBDThink, taking a short drive and reading the codes again is the fastest method for 3100 cases: the first code to return is the root cause.
The Fix
There is no separate repair for 3100; you fix the primary fault and 3100 goes away by itself. This is the order you will most often work through.
• Charge air leak repair: charge pipe, O-ring, couplers and clamps. Low cost and the most frequent root cause.
• Vacuum hoses and boost control solenoid: reconnect what came off, replace a failed solenoid. Low to moderate cost.
• Charge pressure sensor and its connector: clean oxidised pins, replace a drifted sensor. Low cost.
• Wastegate / VTG mechanism: free off the sticking and adjust, renew the actuator if needed. Moderate to high cost.
• Exhaust restriction: cleaning or replacing a blocked catalyst or DPF. High cost.
• Battery and AGM/IBS registration: fix this first if voltage is low. Low cost.
• Turbocharger: overhaul or replacement once mechanical damage is confirmed. High cost.
Once the primary fault is repaired you do not need to chase 3100 separately. Clear the fault memory, complete a few drive cycles and confirm it stays away — if it does, the chain is genuinely broken.
Can You Still Drive With This Code?
3100 itself does not harm the engine; by limiting boost it actually protects it. Still, limp mode can cause sudden power loss, so drive carefully in traffic and avoid manoeuvres like overtaking. The real risk lies in the primary fault behind it: if that fault is 30FE (overboost), the engine is genuinely at risk the moment protection is no longer active.
In short, 3100 is a message telling you "something went wrong, so I switched boost off". Instead of clearing it and driving on, clear the fault memory with OBDThink, take a short drive and read again to expose the real culprit. Once the primary code is repaired, you will not see 3100 again.