Workshop Manuals Factory service & repair Mercedes Benz

Mercedes Benz common faults and how to fix them

Faults that are well known on Mercedes Benz models we hold manuals for: what the owner notices, what causes it, and the pages in our manuals that cover the repair.

Mercedes Airmatic: car sits low, air struts and compressor faults

Symptoms

The car sits low at one corner or across the front after standing overnight, then slowly rises once the engine runs. Later it may not rise at all, and an "AIRMATIC Visit Workshop" or "Airmatic Inoperative" message appears with fault codes. It affects the E-Class (W211), S-Class, ML and R-Class with air suspension.

Cause

The air struts' rubber bellows and seals age and let air out. Mercedes bulletin P-32.22-15A for the W211 E-Class says a front strut that loses its residual pressure after a cold soak sets codes 5500, 5501 or 5507; the compressor is not at fault and must not be replaced. On the ML and R-Class, bulletin T-32.22-50A traces an inoperative system to a blown compressor fuse caused by a chafed compressor cable.

Fix

Read the Airmatic fault codes and find out which corner drops first before buying parts. For the E-Class, the Mercedes air suspension bulletin replaces the leaking front strut. A strut that leaks makes the Airmatic compressor run for too long, so fix leaks first or a new compressor will fail early. On the ML and R-Class, check fuse f108 and the compressor cable route before replacing the compressor.

Repair instructions on this site

Sources: Mercedes-Benz service bulletins P-32.22-15A and T-32.22-50A.

P0016 Mercedes: M272 balance shaft and M273 idler gear wear (2005–2008)

Symptoms

The check engine light comes on with camshaft position codes; Mercedes lists codes 1200 and 1208, which generic scan tools commonly read as P0016 or P0017. The engine may run roughly or misfire, and in the worst case it stops. It affects the M272 V6 in the C, E, CLK, ML, R and SLK models and the M273 V8.

Cause

Mercedes bulletin S-B-00.30/08h says the right-hand camshafts lose their position relative to the crankshaft because of a worn sprocket on the balance shaft (M272) or a worn idler gear for the timing chain (M273). It applies to engines up to set serial numbers. A US lawsuit alleged the gears wear prematurely, typically at 60,000 to 80,000 miles, but it was dismissed because failures fell outside the warranty.

Fix

Check the engine serial number against the bulletin, then remove the timing case cover and inspect the sprocket teeth. On the M272 the M272 balance shaft is replaced together with its counterweight, which are specific to each engine. On the M273 the timing chain idler gear is replaced. The P0016 Mercedes bulletin gives the inspection steps. It is a large job, as the timing drive has to be dismantled.

Repair instructions on this site

Sources: Mercedes-Benz service bulletin S-B-00.30/08h; Wikipedia — Mercedes-Benz M272 engine.

Mercedes conductor plate: 7G-Tronic (722.9) limp mode and harsh shifts

Symptoms

The gearbox drops into limp-home mode, stuck in a single gear with a warning message, and may recover after the engine is restarted. There may be harsh engagement, a delay engaging reverse, or a missing 2–3 shift. Typical codes include 2200, 2201, 2767 and 2768, or 2502, 2505, P0894 and P2711.

Cause

The 7G-Tronic (722.9) is controlled by an electrohydraulic unit in the sump: the valve body with the conductor plate, which carries the gearbox computer and its speed sensors. Mercedes bulletins trace limp-home faults to this unit, and some 2–3 shift faults to a damaged K1 clutch piston. Mercedes later required a diagnostic verification before any valve body or conductor plate replacement.

Fix

Read the gearbox fault codes and adaptation values first. For codes 2200, 2201, 2767 and 2768, the Mercedes limp mode bulletin replaces the electrohydraulic control module. Follow the 722.9 conductor plate verification before replacing it. A new unit must be programmed to the car, and the adaptations reset.

Repair instructions on this site

Sources: Mercedes-Benz service bulletins S-B-27.50/59g, P-27.60/88a and S-B-27.00/120.

Mercedes SBC brake: "Brake Malfunction Visit Workshop" on the E-Class and SL (2003–2006)

Symptoms

A "Brake Malfunction, Visit Workshop" message with the brake warning lamp. The brake pedal travels further and needs much more effort, because the system has dropped into its hydraulic back-up mode. It affects the W211 E-Class and the R230 SL with Sensotronic Brake Control (SBC).

Cause

SBC is an electro-hydraulic brake system: the pedal sends a signal and a pump and accumulator supply the braking pressure. NHTSA recall 05V133000 says it may switch to back-up mode early because of deterioration of the wiring harness connection or premature failure of the hydraulic pump. A follow-up Mercedes campaign (2005070007E) inspected the SBC hydraulic unit on the E-Class and SL and replaced it where needed.

Fix

Check with a Mercedes dealer that both SBC campaigns have been done. The Mercedes SBC recall adds a bracket and new ground wire, and replaces the pump and suction hose where required. The SBC brake unit campaign follows. The SBC unit needs a diagnostic tool for bleeding and programming; it cannot be bled like an ordinary brake system.

Repair instructions on this site

Sources: NHTSA recall 05V133000; Mercedes-Benz campaign 2005070007E.

Mercedes intake manifold: M272 flap lever breaks (2005 on)

Symptoms

The engine light comes on with intake manifold flap or runner control codes, and the engine may feel flat at some engine speeds.

Cause

The M272 V6 has a variable-length intake manifold with flaps that switch between long and short runners. Wikipedia records that the plastic lever operating these flaps can break prematurely. Mercedes supplies the intake manifold only as a complete unit, so the repair is expensive.

Fix

Read the fault codes and look at the flap lever and linkage on top of the M272 intake manifold. Check the flap position sensor and its connector as well, as a sensor fault gives similar codes. If the lever has broken, the factory repair is a new manifold. Repair kits for the lever are sold, but they are not a Mercedes part.

Repair instructions on this site

Sources: Wikipedia — Mercedes-Benz M272 engine.

Repair instructions for every Mercedes-Benz model: Mercedes-Benz workshop manuals