MB Medic Mercedes-Benz Repair Guides, Service, How To DIY
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In this guide (5 sections)
Early M272 engines can suffer premature wear of the balance shaft sprocket. As the sprocket teeth wear, camshaft timing can drift relative to the crankshaft, causing a check engine light, rough running, and Mercedes fault codes 1200 or 1208. A stretched timing chain can cause similar faults, but it is a less common cause when the sprocket is not worn. Confirm the engine serial number, scan the engine control module, check the timing values, and inspect the sprocket before ordering parts.
Balance Shaft
The balance shaft in the M272 engine is the part behind most of these failures. The sprocket on the end of the balance shaft is driven by the timing chain, and on early engines its teeth wear prematurely. As they wear, the camshaft timing drifts and the engine sets fault codes. The repair is a new balance shaft with the revised sprocket, together with the timing chain components.
Timing Chain
The timing chain in the M272 engine can also wear and stretch. If it breaks, this can cause engine performance issues and potentially catastrophic engine damage. To repair this issue, the timing chain, chain guides, and tensioner need to be replaced.
Both of these repairs are complex and take a significant amount of time and labor. Have them done by a qualified mechanic with experience on Mercedes-Benz engines. While the engine is apart, it is a good idea to replace the timing chain, guides and tensioner together and to inspect the camshaft adjusters.
Mercedes-Benz did not recall these engines. It addressed the problem in a dealer service bulletin, and the class action settlement described below covered some repair costs for a limited time.
M272 Balance Shaft Sprocket Problem
The earliest M272 engines show premature wear of the balance shaft gear. On many models, repairing it means removing the engine, which is very expensive, ranging between $3,800 and $5,000. If you have a Mercedes-Benz with the M272 engine, check whether its serial number is higher than 2729..30 468993. Engines through serial number 2729..30 468993 fall within the affected production range, but the serial number alone does not prove the sprocket has failed. Our guide on how to check your engine for the balance shaft problem by VIN shows how to find the serial number and which codes to look for.
There have been a couple of class action lawsuits against Mercedes-Benz. A class action settlement was approved in 2015 and provided limited reimbursement and extended repair coverage. The claim deadline and coverage periods have expired. See the court order granting preliminary approval of the settlement on Justia.
How to Repair the M272 Engine Sprocket
The early M272 was equipped with sprocket gears that wore prematurely and caused the engine to malfunction. The M273 had defective idler gears. Signs of this problem are the check engine light, misfire, and the engine stopping.
Mercedes-Benz engine timing camshaft sprocket on Amazon
M272 Balance Shaft Repair Tips, Part 1
M272 Balance Shaft Repair Tips, Part 2
Confirm the Diagnosis Before the Engine Comes Out
Codes 1200 and 1208 (P0016 and P0017 on a generic reader) can also come from a failed camshaft position sensor or a sticking camshaft adjuster, both of which are far cheaper than a balance shaft. Clear the codes and see whether they come straight back, then compare the camshaft position values in live data with the specification. The UCAN-II Pro reads the Mercedes engine codes and the camshaft live data on the M272. If the readings point at a sensor, see our camshaft position sensor guide.
Before you buy parts, scan every control module, not just the engine. It shows the root fault behind the warning lights and tells you whether the problem is still active. See how to do a full health check.
