P06B1

Code

Generic P — Powertrain

Sensor Power Supply A Circuit Low

Brand: Generic

Type: P — Powertrain

Views: UK: 23 EN: 38 RU: 29

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Page language: EN

Causes

Low or missing 5 V reference/sensor supply
Short to ground on the sensor power/signal wiring
Open or high resistance in wiring or connector
Poor sensor ground or chassis ground
Failed sensor
Blown fuse or failed power relay providing sensor supply

Symptoms

Malfunction Indicator Lamp (MIL) or CEL illuminated
Poor engine performance, hesitation or reduced drivability
Sensor-related systems not operating correctly (depends on which sensor uses Supply A)
Stored diagnostic trouble codes for the affected sensor(s)
Intermittent operation or limp-in mode depending on vehicle

What to check

Read freeze frame and all stored codes; note related sensor codes
Visually inspect wiring and connectors for damage, corrosion, bending or pin push-out
Check relevant fuses and relays for the sensor reference supply
Back-probe sensor connector and measure reference voltage, sensor output and ground
Perform continuity and resistance checks between sensor and ECU pins
Wiggle test wiring while monitoring voltages/scan tool for changes

Signal parameters

Sensor reference supply (typical): 5.0 V ± 0.25 V (acceptable ~4.75–5.25 V)
Sensor output: typically 0.1–4.9 V depending on sensor type and condition
Sensor ground: close to 0 V (
Open-circuit: infinite resistance; short-to-ground: near 0 Ω to chassis ground
Wiring harness continuity: low ohms (typically

Diagnostic algorithm

Retrieve DTCs and freeze-frame; note which sensor(s) use Sensor Power Supply A and any related codes.
Inspect connectors, wiring harness and sensor for obvious damage, corrosion, loose pins or water intrusion; repair as needed.
Check fuses and relays that supply the sensor reference; replace if blown or faulty.
With key ON (engine off), back-probe the sensor connector: measure the reference supply voltage, sensor output and ground. Compare to expected values.
If reference supply is low or absent at the sensor, trace wiring back toward the ECU: check for short-to-ground or high-resistance/open using continuity and resistance checks.
Measure continuity between sensor ground and ECU ground and between sensor supply pin and ECU supply pin. Repair any high resistance or opens.
If wiring checks good at the connector, disconnect the sensor and measure the reference at the harness side. If present at harness but not at sensor when connected, suspect sensor failure.
If possible, substitute a known-good sensor or connector jumper to confirm sensor vs wiring/ECU.
If wiring and sensor are good and reference is low only at ECU, suspect internal ECU power/supply fault — perform ECU bench tests or consult manufacturer procedures before replacing ECU.
After repairs, clear codes and perform a test drive; verify that the DTC does not return and that related systems operate correctly.

Likely causes

Blown fuse or faulty power/ignition relay supplying the sensor reference
Damaged, corroded or disconnected connector at the sensor
Short to ground in the sensor power or signal wiring
Faulty sensor (internal short or open)
Bad ECU sensor supply circuit

Fault status

⚠️ Status

Sensor Power Supply A Circuit Low — reference/supply voltage to sensor is below expected threshold. Possible causes: blown fuse/relay, short-to-ground, open/high resistance wiring, faulty sensor, or ECU internal fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours