Where Is the DME Relay Located in a 1987 Porsche 911 Carrera? A Detailed Guide

The DME (Digital Motor Electronics) relay is a critical component in your 1987 Porsche 911 Carrera’s fuel injection and ignition system. When it fails, the engine may crank but not start, or it may stall unexpectedly. Knowing its exact location and how to replace it can save you time and frustration. This guide covers everything you need: where the relay resides, how to access it, symptoms of a bad relay, and what to consider when buying a replacement.

What Is the DME Relay and Why Does It Matter?

The DME relay is essentially a switch that provides power to the engine control unit (ECU) and the fuel pump. In the 1987 911 Carrera (G-series, 3.2L engine), the relay is often a silver or black Bosch unit. When the ignition is turned on, the relay energizes, sending 12 volts to the ECU and fuel pump. If it fails, the car will not run.

Function of the DME Relay

• Powers the ECU – Without relay operation, the computer cannot control injection or ignition.
• Activates fuel pump – The relay closes the circuit to the fuel pump relay (or directly to the pump) during cranking and running.
• Provides a reliable switching path – The relay handles high current that would otherwise overload the ignition switch.

Common Failure Symptoms

• Engine cranks but won’t start – This is the most frequent complaint. The starter spins, but no fuel or spark reaches the cylinders.
• Intermittent stalling – The car may run fine for a while, then suddenly cut out, especially when hot (thermal failure of relay contacts).
• No fuel pump hum – With the ignition on, you should hear the pump prime for 1–2 seconds. If silent, the relay may be faulty.
• No check engine light on bulb check – The ECU gets no power, so the warning lamp stays dark.

Exact Location of the DME Relay in a 1987 Porsche 911 Carrera

The DME relay in a 1987 Carrera is located inside the passenger compartment, not the engine bay. There are two common positions depending on production date and options, but the most reliable spot is behind the right-hand (passenger side) footwell panel.

Behind the Passenger Side Footwell Panel

1. Remove the carpeted kick panel – Open the passenger door. Look at the footwell area against the firewall. There is a shaped plastic or fiberboard cover held by two or three 10mm bolts or plastic push-pins. Carefully pry or unscrew it.
2. Locate the relay board – Behind this panel, you will see a vertical metal bracket holding several relays and a fuse block. The DME relay is usually the silver or black rectangular relay with a large Bosch logo. It may be labeled "DME" or have a part number like 0 332 020 150.
3. Identify by position – On many 1987 models, the DME relay is the one closest to the door, above the fuse panel. If there are two identical relays, the DME is often the upper or outer one.

Alternative Location: Under the Dashboard (Driver Side)

Some 1987 Carreras (especially early production) have the DME relay under the driver’s dashboard, near the steering column. To check:

• Reach up above the driver’s footwell, behind the knee bolster panel. There is a horizontal relay bracket. If you see a Bosch relay with a central tab (for removal), that is likely the DME relay.
• Caveat: This location is less common for 1987; the passenger footwell is the primary spot. If you don’t see it there, you may have a later model or one fitted with aftermarket alarm systems that relocate the relay.

Visual Identification of the DME Relay

The correct relay is a five-pin unit (four pins visible, one central) measuring about 1.5” x 1.5” x 1”. It often has a Bosch logo and the part number 0 332 020 150. Some aftermarket units use the same footprint. If you are unsure, compare the colors of the wires going into the relay base: the DME uses red (constant 12V), brown (ground), black/yellow (ignition switch), and two others (to ECU and fuel pump).

Step-by-Step Replacement Guide

Replacing the DME relay is a straightforward DIY task if you are comfortable accessing the footwell area. No special tools are needed beyond a basic socket set or screwdriver.

Tools Needed

• 10mm socket or wrench (for panel bolts)
• Trim removal tool (or flathead screwdriver wrapped in tape)
• New DME relay (OEM Bosch #0 332 020 150 or equivalent)
• Flashlight

Safety Precautions

• Disconnect the battery negative terminal before working on the relay to prevent shorting or accidental power to the fuel pump.
• Wait at least 10 minutes after disconnecting the battery for the airbag system (if equipped) to discharge.

Removing the Old Relay

1. Disconnect battery negative.
2. Remove the passenger footwell panel as described above.
3. Locate the DME relay. It is usually held in place by friction (no locking clip). Grasp it firmly and rock it side-to-side while pulling straight out. If it’s tight, use a small flathead screwdriver to gently pry between the relay base and the socket.
4. Inspect the socket for corrosion or bent pins. Clean with electrical contact cleaner if needed.

Installing the New Relay

1. Align the new relay’s pins with the socket. Note the orientation: the relay has a small tab or notch that matches the socket’s keyway. Do not force it.
2. Push the relay firmly into place until it clicks or sits flush.
3. Reinstall the footwell panel and tighten bolts.
4. Reconnect battery negative.
5. Test: Turn ignition to “on” and listen for a 1–2 second fuel pump prime. Then attempt to start the engine. If it starts and runs smoothly, the replacement was successful.

Choosing a Replacement DME Relay

When buying a new DME relay for your 1987 Carrera, you have two main options: OEM Bosch or aftermarket equivalents. Quality matters because a cheap relay can fail prematurely and leave you stranded.

OEM vs. Aftermarket

• Bosch OEM: Original equipment part #0 332 020 150 (or 0332020150). Reliable, exact fit, made to Porsche specifications. Typically costs $50–$80.
• Aftermarket: Brands like Standard Motor Products (SMP), Intermotor, or others offer compatible relays. They are cheaper ($15–$35) but may have different current ratings or build quality. If you choose aftermarket, verify pin configuration and that it includes a suppression diode (to prevent voltage spikes).

Recommended Specifications

• Voltage: 12V
• Amperage: at least 30A for the fuel pump circuit
• Number of pins: 5 (two 30/87, one 85, one 86, one 87a or 87)
• Suppression diode: Highly recommended to protect the ECU

Avoid “universal” relays with spade terminals that require splicing. They are unreliable and not plug-and-play.

Final Recommendation

For your 1987 Porsche 911 Carrera, the DME relay is most likely located behind the passenger side footwell panel. If your car exhibits starting issues, this is the first component to check. A faulty relay is a common failure point on these classic 911s, especially as they age.

We strongly recommend using an OEM Bosch relay for long-term reliability. It’s a small investment compared to the cost of a tow or unexpected breakdown. Always disconnect the battery before handling the relay, and take your time when prying it out to avoid damaging the socket.

If you have replaced the relay and the problem persists, the issue may be elsewhere—the fuel pump relay itself, the main power supply (fuel pump fuse), or the ECU. However, in the majority of cases, a fresh DME relay will get your Carrera running again. Keep a spare in your glovebox for peace of mind on the road.