📥 Bosch ME20 Verified Pinout Reference Card (text version below – copy/save):
ME20 CONNECTOR A (55-pin): A1: Relay out | A2: Batt+ | A3: Ign+ | A4: Sen Gnd | A5: Pwr Gnd A18: CKP+ | A19: CKP- | A32: CMP | A33: TPS | A40/41: Knock A54: CAN H | A55: CAN L
ME20 CONNECTOR B (16-pin): B1-4: Injectors 1-4 | B9: Coil 1+4 | B10: Coil 2+3
Note: This document summarizes a verified pinout for the Bosch ME20 engine control unit (ECU), along with wiring notes, common signals, testing tips, and safety/diagnostic considerations. Use it for reference during bench-testing, wiring harness repair, diagnostics, or retrofit projects. Confirm with continuity testing and the specific ECU label/connector before making permanent wiring changes. bosch me20 pinout verified
The ME20 relies on precise voltage signals to calculate fuel trims.
Sometimes people confuse ME pinouts with Simos (like Simos 18), but the Bosch ME housing shapes (the "Sandcastle" design) are distinct. The pin numbering (1-xx on one side, xx-yy on the other) is counter-intuitive compared to Japanese ECUs.
Are you working on a specific project (like a Volkswagen/Audi 1.8T/2.0T, or a Volvo) or just documenting the hardware capabilities? I’d be happy to cross-reference any specific pins you found "interesting." 📥 Bosch ME20 Verified Pinout Reference Card (text
| Myth | Truth | |------|-------| | Pin A4 is chassis ground | ❌ A4 is sensor ground – connecting to chassis will corrupt TPS/MAP readings | | Any 12V on injector pins is fine | ❌ Injector pins are ground-switched – backfeeding 12V destroys the driver IC | | CAN pins are unused without immobilizer | ❌ CAN is still required for engine RPM to instrument cluster | | ME20 and ME7.4 pinouts are identical | ❌ ME7.4 has additional wideband O2 pins – swapping ECUs requires repinning |
Published by: AutoDiag Tech Journal
Reading time: 10 minutes
If you are working on a late-1990s to mid-2000s European vehicle—specifically from Peugeot, Citroën, Renault, Fiat, or early BMW/Mini—you have likely encountered the Bosch ME20 engine control unit (ECU). This ECU is notorious for wiring harness degradation, corroded terminals, and sensor ground faults. Searching for a reliable, verified pinout diagram often leads to forums with conflicting information. Note: This document summarizes a verified pinout for
After cross-referencing Bosch technical documents (ESI[tronic]), OEM wiring diagrams from PSA Group, and physical continuity tests on five separate ME20.2 and ME20.4 units, we have compiled the definitive verified pinout for the Bosch ME20 series.
Disclaimer: Always verify with your specific vehicle's wiring diagram. Pin functions can vary slightly between ME20.2, ME20.4, and ME20.6 variants. This guide covers the 64-pin and 88-pin configurations (ME20.4/6).