W116/R107 280 won't start? Check the D-Jetronic control unit
The D-Jetronic was Bosch's first electronic gasoline injection system – and therefore also the first in which a control unit alone decides the mixture. Anyone driving an early W116 280 SE or R107 280 SL today often faces the same question when it won't start: is it the ignition, the fuel pump, a sensor – or the control unit itself? This guide shows how you can narrow down the cause before you spend money on parts.
Bosch control unit 0 280 001 008 of the D-Jetronic for the Mercedes 2.8-liter six-cylinder M110.
Symptoms: How can you tell that a D-Jetronic control unit is faulty?
The analog control unit calculates the injection pulses for the six-cylinder. To do so, it evaluates the intake manifold pressure sensor, the intake air and coolant temperature sensors and the throttle valve switch, and it controls the injectors and the fuel pump relay. The system has no air flow meter. If the control unit fails, it is therefore usually not only the injection pulse that is missing, but also the pump control.
| Symptom | Likely cause |
|---|---|
| Engine cranks but won't start; spark present, spark plugs stay dry | Control unit (no injection pulse) or control of the fuel pump relay |
| Engine misfires sporadically, especially after jolts or when hot | Control unit or contact at the circuit board edge connector |
| Engine runs noticeably too rich or too lean, even though sensors and vacuum hose are fine | Control unit (faulty pulse calculation) |
| Engine won't start, spark plugs dry – and no spark | More likely the ignition system, e.g. ignition control unit of the transistorized ignition |
| Later 280 (K-Jetronic) runs poorly during warm-up | No control unit installed – more likely the warm-up regulator of the K-Jetronic |
Important for telling them apart: only the early 280s with D-Jetronic have an electronic injection control unit. The later 280s with K-Jetronic work purely mechanically-hydraulically – this guide does not apply to them.
Causes: Why does the control unit fail after decades?
Today the D-Jetronic control units are around 50 years old. As with any analog electronics of this generation, components on the circuit board age, solder joints can develop hairline cracks from temperature changes and vibration, and the contacts on the edge connector oxidize. In addition, there is consequential damage from faults in the vehicle electrical system, such as voltage spikes when working on the battery or a short circuit in the wiring harness. A fault often shows up sporadically at first, before the engine no longer starts at all.
Check it yourself: 5 steps before you replace the control unit
- Check connector and ground: The control unit is connected via the wiring harness's circuit board edge connector and secured with a knurled screw. Is the connector seated firmly, and are the contacts clean? A loose or corroded connector causes exactly the typical misfires – and costs nothing.
- Listen for the fuel pump: Does the pump start up when you crank the engine? If not, check the fuse and pump relay first. If the pump stays silent despite an intact fuse, the control signal from the control unit may also be missing.
- Check sensors and vacuum: Check the vacuum hose to the intake manifold pressure sensor for cracks, and measure the temperature sensor and throttle valve switch. A faulty sensor feeds the control unit wrong values – the unit itself is then innocent.
- Check the injection pulse: Use a diode test lamp on the disconnected connector of an injector while cranking to check whether pulses arrive. If no pulses arrive with an intact supply and intact sensors, the control unit is under suspicion.
- Cross-check: The most reliable confirmation is a test with a working control unit with the same Bosch number. If the engine runs with it, the diagnosis is clear.
Solution: genuine control unit with the matching Bosch number
New control units for the D-Jetronic have not been available for a long time. We have the Bosch control unit 0 280 001 008 (Mercedes number A 000 545 54 32) in stock as a used genuine part – not aftermarket. The units come in the yellow chromate-plated sheet-metal housing with heat sink, and the gold-plated circuit board contacts are clean. Three pieces are available; the price of 249 € applies per piece. The condition is described honestly on the product page, and the photos show a real unit.
Please compare before buying: The Bosch control unit 0 280 001 015 also runs under the same Mercedes number A 000 545 54 32. What matters is the number on your old part. The 0 280 001 008 does not fit, among others, the 250 CE (M114), the W116 350 or the 450 models W116/R107 – these have their own control units.
Bosch 0 280 001 008 · Mercedes A 000 545 54 32
D-Jetronic control unit for W116 280 SE/SEL, R107/C107 280 SL/SLC and W114 280 E/CE (M110)
249,00 € per piece · Genuine used part · 3 pcs in stock
To the control unit →You can find more control units and relays for classic Mercedes in our category Mercedes relays & control units, and parts specifically for the S-Class in the category W116.
Compatible vehicles
| Model series | Models | Note |
|---|---|---|
| S-Class W116 with D-Jetronic (1972–1976) | 280 SE, 280 SEL (M110) | D-Jetronic only |
| SL R107 / SLC C107 with D-Jetronic (1974–1976) | 280 SL, 280 SLC | D-Jetronic only |
| /8 W114 with D-Jetronic (1972–1976) | 280 E, 280 CE | D-Jetronic only |
Later 280s with K-Jetronic do not have an electronic injection control unit. If in doubt, send us your VIN – we will check free of charge whether the part fits.
FAQ
How do I recognize a faulty D-Jetronic control unit?
Typical signs: the engine cranks, a spark is present, but the spark plugs stay dry because no injection pulses arrive. Sporadic misfires can also come from the control unit or its edge connector. The diagnosis only becomes certain once the supply, sensors and connectors are fine and still no pulse arrives at the injectors.
Which vehicles use the control unit 0 280 001 008?
The Mercedes six-cylinder M110 with 2.8 liters and D-Jetronic: W116 280 SE and 280 SEL, R107/C107 280 SL and 280 SLC, and W114 280 E and 280 CE, in each case from the years with D-Jetronic.
Does every control unit with the number A 000 545 54 32 fit?
The Bosch control unit 0 280 001 015 also runs under this Mercedes number. So compare the Bosch number on your old part before you order.
Does my 280 SE even have an injection control unit?
Only if it was still delivered with D-Jetronic. The later 280s with K-Jetronic work without an electronic injection control unit – there, the warm-up regulator, fuel distributor and cold start valve are the usual suspects.
Do I have to send in my old control unit?
No. No core deposit is charged and you don't need to return anything.
KFZTeile-Thot is a specialist business for tested and refurbished Mercedes parts with its own test benches – specializing in Mercedes classics, with over 1,000 positive eBay reviews. Questions about the D-Jetronic control unit or the matching Bosch number? Call us: +49 179 8991069 (Mon–Fri 8 am–6 pm) or use the contact form. More guides for the early six-cylinders: Check the ignition control unit TSZ-k and W116 engine control unit A0005452932.