Mercedes-Benz ML430 Bosch ECU 0261206303 With a Badly Soldered Chip and No Start

Our testing rig gave two verdicts on this Bosch engine ECU, number 0261206303, from a 1999 Mercedes-Benz ML430 that would not start. The first came after we reworked a badly soldered chip, and it was a refusal. The second came after we replaced the chip and reflashed the unit, and it was a pass, with cranking and starting simulated on the rig.

The history that came with the unit

Before it reached us, work had been carried out on the ECU elsewhere, which involved fitting an aftermarket chip to it. Since that work, the ML430 had not started. The customer suspected the ECU had been damaged, and they sent it to us to find out.

That was the whole history we had to go on.

First verdict: solder reworked, data refused

Initial inspection found the chip badly soldered in place. We reworked the solder. Rework at that scale is carried out under a microscope with temperature-controlled rework equipment, by our own engineers in our UK workshop.

With the joint reworked, we put the unit on our testing rig. We could not load data onto it. Reworking the solder had not been enough on its own, and the rig’s refusal left us suspecting that the chip itself was damaged.

Second verdict: a new chip, a reflash and a pass

We replaced the chip and reflashed the unit, then put it back on our testing rig. This time the ECU passed. On the rig we were able to simulate cranking the engine and starting the vehicle.

The job record ends at that pass and says nothing about the car afterwards, so this page does not either.

No repair of ours is complete until the unit passes final testing, and this one was returned to the customer once it had. Our engineers’ work on it carries warranty cover for 24 months, held by the customer who sent it in.

0261206303 beyond this one job

This ML430 is fitted with a Bosch ME2.0 engine ECU. Away from this job, ML430 is on record for 0261206303. 0261206303 is also on record with the Mercedes number A0265456932. Our page for Mercedes-Benz engine ECUs in that Bosch range has a table that prints the two side by side.

If an engine ECU you have carries the Bosch number 0261206303, that table is a good place to check it against. Neither detail says what is wrong with a particular unit; that only comes out of diagnosis.

From your post to our bench

We work by post, taking engine ECUs in from across the UK. Each unit is logged, visually inspected and electrically tested, then taken through diagnostics specific to its fault. We contact you with what we find and a quote, and no chargeable work starts until you authorise it.

To ask for a quote, contact us via the Repair Form, noting the Bosch number and the symptoms. For a Mercedes-Benz unit with a different number, see other Mercedes-Benz engine ECUs sent to our workshop. What We Repair introduces some of the engine ECU families we work on.