C3989 Mercedes-Benz Auto Trouble Code

C3989 Mercedes-Benz Auto Trouble Code on vehicles with electronically controlled automatic transmissions, the 3-4 shift solenoid is responsible for actuating the hydraulic circuits to activate clutches or bands that change gears inside the automatic transmission.

The crank but won't start condition, along with the trouble codes may make you think you've got a PATS anti-theft system problem. However, Ford reports that these codes are all related to software bugs. The only way around the problem is to reprogram the PCM with the latest software.

C3989 Mercedes-Benz Possible Solution:

Excessive air inflow can be caused by a vacuum leak, a dirty sensor or, an exhaust gas recirculation valve not closing properly. If the problem is not enough fuel, the culprit may be dirty injectors or fuel filters, a weak fuel pump or a leaky fuel pressure regulator. The lean fuel mix error may be accompanied by rough idling, engine misfires, hesitation during acceleration and overall poor engine performance.

C3989 Mercedes-Benz Description For All Models :

C3989 Mercedes-Benz Trouble Repair :

With C3989 Mercedes-Benz code so start with the basics like a fuel pressure and fuel volume test. Or, you can start on the electrical side by doing a voltage drop on both the power and ground connections for the fuel pump. Some shops are reporting corrosion on the fuel pump ground that reduces power and fuel pressure.

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