Open circuit in the reference voltage E wiring, such as a broken wire or corroded connector terminal; Failed sensor internally shorted or open, pulling the reference voltage down or interrupting it; Loose or damaged ECM connector pins for the reference voltage circuit; Water intrusion or corrosion in a harness connector along the reference voltage path; Aftermarket accessory improperly tapped into the reference voltage line; ECM internal fault, though this is less common

DTC codes / P06xx · Computer and output circuits / P06D2

P06D2Sensor Reference Voltage E Circuit/Open

Q: What does code P06D2 mean?

Sensor Reference Voltage E Circuit/Open. P06D2 means the engine control module (ECM) has detected an open circuit on the sensor reference voltage E line, which is a regulated 5-volt supply shared by multiple sensors. The ECM monitors this line and sets the code when the voltage falls outside its expected range, indicating a break in the wiring or a failed component drawing the reference voltage down.

P06D2 means the engine control module (ECM) has detected an open circuit on the sensor reference voltage E line, which is a regulated 5-volt supply shared by multiple sensors. The ECM monitors this line and sets the code when the voltage falls outside its expected range, indicating a break in the wiring or a failed component drawing the reference voltage down.

SystemPowertrain

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Illumination of the check engine light, often with no other noticeable symptoms
Rough idle or poor engine performance if the affected sensors include the throttle position or manifold absolute pressure sensor
Reduced fuel economy or altered shift quality as the ECM substitutes default values
Intermittent stalling or hesitation during acceleration
Failed emissions test due to incomplete readiness monitors
Other sensor-related codes stored simultaneously, such as P06D3 or P0641

Common causes, most likely first

Open circuit in the reference voltage E wiring, such as a broken wire or corroded connector terminal
Failed sensor internally shorted or open, pulling the reference voltage down or interrupting it
Loose or damaged ECM connector pins for the reference voltage circuit
Water intrusion or corrosion in a harness connector along the reference voltage path
Aftermarket accessory improperly tapped into the reference voltage line
ECM internal fault, though this is less common

How to diagnose and fix it

Verify the code with a scan tool and check for other stored codes that may indicate a shared reference voltage issue
Inspect the wiring harness and connectors for the affected sensors, looking for chafing, corrosion, or loose pins
Measure the reference voltage at each sensor connector with a digital multimeter; it should be close to 5 volts with the key on
Disconnect sensors one at a time to see if the reference voltage returns to normal, isolating a faulty sensor
Perform a voltage drop test on the reference voltage circuit to locate excessive resistance
Repair or replace any damaged wiring or connectors, then clear the code and verify the repair
If the reference voltage is still incorrect after all external checks, test the ECM and replace if necessary

Reference voltage faults often misdiagnosed

A single shorted sensor on the shared reference voltage line can disable multiple sensors and set several codes, so always check all sensors on that circuit before replacing parts.
The reference voltage E circuit may be shared with the throttle position sensor, accelerator pedal sensor, and manifold absolute pressure sensor, so symptoms can vary widely.
Corrosion inside a connector that looks fine from the outside is a common cause, especially in areas exposed to road splash.
Aftermarket alarms or remote starters tapped into the reference voltage line can introduce an open or short that sets this code.
The ECM may set this code intermittently if the open circuit is temperature or vibration sensitive, so wiggle-test the harness while monitoring live data.

Can I keep driving with P06D2?

If the check engine light is on but the engine runs normally, you can drive cautiously to a repair shop, but avoid heavy acceleration or towing. If the engine runs poorly, stalls, or enters limp mode, stop driving and have the vehicle towed to prevent safety risks.

Tools that help

Tools we recommend are in the Auto Veteran shop on Amazon. As an Amazon Associate we earn from qualifying purchases.

Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.