P0699

Code

Generic P — Powertrain

Sensor Reference Voltage C Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 26 EN: 32 RU: 24

AI status

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Page language: EN

Causes

Short to battery voltage on the Sensor Reference Voltage C wire
Faulty sensor(s) tied to the Reference C circuit
Damaged harness (chafing, pinched, exposed conductor) causing a short to Vbatt
Poor or missing ground(s) or high-resistance ground connection
Corroded, loose or damaged connector pins at sensor(s) or PCM
Internal PCM/regulator fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated (check engine light)
Stored or pending P0699 and possibly related sensor codes
Erratic sensor readings for sensors using Reference C
Poor idle, hesitation, stalling or reduced drivability if affected sensors are critical
Multiple sensors on the same reference circuit showing faults simultaneously

What to check

Retrieve freeze frame data and all stored/pending codes; note related sensor codes
Visually inspect wiring harness and connectors for the sensors using Reference C
Identify which sensors share the Reference C circuit from the wiring diagram
Backprobe the sensor reference pin with key ON, engine OFF and measure voltage to ground
Disconnect sensors on the Reference C circuit one at a time to see if voltage returns to normal or codes clear
Inspect for aftermarket devices or repairs that may have tapped into the reference circuit

Signal parameters

Expected sensor reference voltage: ≈5.0 V (typical 4.5–5.5 V range) with key ON, engine OFF
Voltage should be stable (low ripple); no large transients or spikes
When sensors are disconnected, reference should remain within expected range (indicates PCM/regulator is driving it)

Diagnostic algorithm

Read codes, freeze frame and live data. Note other codes that share the same sensor reference. 2) Obtain wiring diagram to identify all sensors on Reference C and pin locations at sensors and PCM. 3) Visually inspect connectors and wiring for damage, corrosion, chafing, or aftermarket taps. 4) With key ON (engine OFF), backprobe the reference C pin at a sensor connector and measure voltage to ground with a DMM. Compare to expected ~5 V. 5) If voltage is high, disconnect each sensor on the reference C circuit one at a time while monitoring the reference voltage — if disconnecting a particular sensor returns voltage to normal, suspect that sensor or its shorted lead. 6) If disconnecting sensors does not restore normal voltage, test at the PCM reference output pin. If the PCM pin reads high, suspect PCM/regulator fault or a short to battery on the harness between PCM and sensors. 7) Perform wiggle tests and flex harness while monitoring voltage to reproduce intermittent shorts. 8) If wiring is faulty, repair or replace affected sections and re-test. 9) If wiring and sensors check good and PCM output remains out of range, consider PCM replacement only after confirmation with bench test or manufacturer guidance. 10) Clear codes and test drive to confirm repair. Use an oscilloscope if transient or ripple issues are suspected.

Likely causes

Short to battery on reference C wiring (most common)
Corroded/loose connector at a sensor on reference C
Faulty sensor connected to reference C
Harness damage where it contacts chassis or hot circuits
PCM output/regulator failure (less common)

Fault status

⚠️ Status

PCM reports Sensor Reference Voltage C circuit is higher than expected. Check wiring/connectors, sensors on that reference circuit, and PCM reference output.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-3.0 hours

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