P2687: Fuel Supply Heater Control Circuit/Open

Diesel engines warm the fuel at the filter so that wax crystals do not block it in frost. P2687 says the control line of that heater is open. In GM's diesel ECM tables the engine computer switches the heater relay with a low-side driver and judges the off-state voltage; more than 200 kOhm between pin and ground means open. The 2014 version (14OBDG04) needed 11 V for 3 s and 2 s of fault, Type B with MIL; the 2017 and 2020 versions use 10 bad readings out of 20 at 100 ms and rate it Type C without lamp. Ford used the same code differently: its 2015 and 2016 diesel summaries apply P2687 to the vaporizer glow plug of the 3.2 L Transit's downstream injection, open if the line sits at 2.9 to 3.2 V for 5 s; from 2017 that fault moved to P269B.

Low severity. Can I keep driving?You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.

Symptoms

Hard starting or stalling in severe cold
Power loss from a waxed fuel filter
Often no warning lamp, depending on model year

Most likely causes

Heater relay coil open or relay not seated
Broken control wire or corroded terminal at the filter housing
Heater element open where it is switched directly without a relay

What to check, in order

Start with the simplest. You can tick off each step.

Check the connector and wiring
Check the continuity of the wire between the component and the control module.
Use live data to compare the reading with actual conditions
Measure power, ground, and signal
Replace the sensor if the circuit is good

Good to know

Repair difficulty: medium
It affects emissions.

What each character of P2687 means

P: Powertrain: engine and transmission
2: Generic code: same on every make
6: Control modules and outputs
87: Specific fault in that system

Frequently asked questions

Can I keep driving with code P2687?

You can normally keep driving. If it affects the fuel level, do not trust the gauge and refuel earlier than usual.

What causes code P2687?

The most common causes are: heater relay coil open or relay not seated; broken control wire or corroded terminal at the filter housing; heater element open where it is switched directly without a relay.

Related codes

Sources

Values and procedures vary by manufacturer. If it affects brakes, steering, fuel or high voltage, see a professional. Updated: 2026-11-04. How we build these pages.