P0698: Sensor Reference Voltage C Circuit Low

The engine module feeds sensors from several regulated 5 V reference circuits; a short at one sensor pulls the whole circuit down, so all its sensors report at once – unplug them one by one to find the culprit. Which sensors hang on circuit C depends on the maker – pedal sensor 2 is common to all: GM 2016–2025 feeds only pedal sensor 2 from it, the Saab 9-4X also the MAP sensor, the Saab 9-5 2.0 L turbo also throttle, crankshaft and A/C pressure sensors, and Bentley's 2026 Bentayga V8 lists its own set. P0698 means reference C is too low – usually a short to ground. GM's 6.6 L Duramax LB7/LLY sets it below 4.7 V for 2 s, GM Europe's 2.0 L turbo after 1 s or 10 s cumulative, each with the lamp in the first trip; newer GM engines report it as P0697.

Medium severity. Can I keep driving?It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

Symptoms

Check engine light
Several sensor codes at once (pedal, throttle, pressure)
Electronic throttle limp mode, reduced power
Possibly starting problems

Most likely causes

Short in the wire or sensor of a connected sensor
Chafing or water in harness or connector
A connected sensor faulty internally
Module internal voltage regulator

What to check, in order

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

Check the battery and grounds
With the connector unplugged, check whether the signal wire is making contact with ground.
Clear the code and see if it returns
If it is a reference voltage code, disconnect sensors one at a time and see if the voltage recovers
Check whether a software update is available
Do not replace the control module without a full diagnosis

Good to know

Repair difficulty: medium
It can trigger limp mode.
It affects emissions.

What each character of P0698 means

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

Frequently asked questions

Can I keep driving with code P0698?

It depends on the symptoms. If the car is running normally you can go to a repair shop; if it goes into limp mode, drive as little as possible.

What causes code P0698?

The most common causes are: short in the wire or sensor of a connected sensor; chafing or water in harness or connector; a connected sensor faulty internally.

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.