Limp mode when loaded on hills, whoosh under boost
- Make and model
- Mercedes-Benz Sprinter 316 CDI
- Year
- 2013
- Engine
- 2.1 CDI (OM651)
- Fuel
- Diesel
- Mileage
- 262,000 km
Customer complaint
The van goes into limp mode when fully loaded on hills. The driver hears a whoosh when accelerating hard. It clears after restarting the engine.
Under loadIntermittent
Fault codes
| Code | Description | Status |
|---|---|---|
| P0299 | Turbocharger/Supercharger "A" Underboost Condition | Confirmed |
Measurements and live data
| Parameter / measurement | Measured | Expected |
|---|---|---|
| Boost, specified / actual, full load | 2,350 / 1,700 mbar | actual within about 100 mbar |
Tests performed
- Smoke test of the charge-air side under pressureSmoke from a split on the inside of the hose between intercooler and throttle body
- Road test fully loaded, boost loggedAfter the repair actual boost follows specified at full load
Solution
Root cause
Charge-air hose split on the inside of a bend, softened by oil vapour.
Repair
Replaced the charge-air hose with new clamps, cleaned the oil out of the intercooler and pipes, cleared the code. Fully loaded road test: no limp mode.
Parts
Charge-air hose, clamps
Labour time
1 h
Lesson learned
A split on the inside of a bend only opens under boost: smoke-test under pressure instead of looking at the hose at rest.
Training case: the usual fix for this fault, not a confirmed repair on a specific car.
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