Today’s job was EHA replacement (Electro-Hydraulic Actuator) on my 1987 560SEL. The EHA is part of the KE Jetronic fuel injection system and makes minute adjustments to the air/fuel mixture. One of the sources for these adjustment is the oxygen sensor, if present. The EHA can leak either because the o-rings between the EHA and the fuel distributor have gone hard, or because of internal leaks in the EHA itself. In the case of my car, it looked like the EHA was leaking, not the o-rings.
The EHA is still available from Bosch, but it is not cheap. Still, I […]