Code
P0698
Generic
P — Powertrain
Sensor Reference Voltage C Circuit Low
Views:
UK: 11
EN: 17
RU: 13
AI status
Completed
Completed
100%
Causes
- Poor or low battery/charging system voltage
- Blown or open fuse supplying the PCM/reference regulator
- Poor PCM power or ground connections
- Damaged, chafed or shorted wiring on reference circuit C (short to ground)
- Corroded/loose connector at sensor(s) or PCM
- Faulty sensor(s) tied to the reference circuit
Symptoms
- Malfunction indicator lamp (MIL) illuminated
- Multiple sensor-related trouble codes or erratic sensor readings
- Engine may run rough, reduced performance or stumble (depending on affected sensors)
- In some cases poor fuel economy or difficulty starting
- Some vehicle systems that rely on sensors on this reference may operate unpredictably
What to check
- Scan for additional DTCs and record freeze-frame/data PIDs to identify affected sensors
- Verify battery voltage with key ON and engine running (should be ~12.4–14.8 V)
- Inspect fuses and relays related to PCM and sensor power/reference
- Visually inspect wiring harnesses, connectors and grounds for damage/corrosion
- Back-probe the sensor reference pin at the sensor connector and at the PCM to compare voltages
- Check continuity and resistance between sensor connector reference pin and PCM reference pin
Signal parameters
- Nominal sensor reference voltage: ~5.0 V (typical acceptable range 4.75–5.25 V)
- Low condition typically flagged when reference falls below ~4.4–4.6 V (threshold varies by manufacturer)
- Open-circuit continuity: very high resistance / OL between PCM reference pin and sensor connector
- Short-to-ground: near 0 Ω between reference circuit and ground
- With key ON, engine OFF: reference should be present and stable near nominal value
Diagnostic algorithm
- Retrieve all stored DTCs and freeze-frame data. Note which sensors share reference circuit C.
- Verify battery/charging system voltage. Charge battery or repair charging if low before further testing.
- Inspect fuses, PCM power/ground connections and visible wiring for damage or corrosion; repair as needed.
- With key ON (engine OFF), back-probe the reference C pin at the PCM and at each affected sensor connector. Compare voltages; they should be within a few tenths of a volt of each other and near ~5 V.
- If reference is low at PCM pin, suspect PCM power/ground, fuse, or internal regulator. If low only at sensor connector(s), suspect wiring/connector between PCM and sensor.
- Check continuity and resistance between PCM reference pin and sensor connector. Look for high resistance or open circuit. Check for short to ground (measure resistance to ground).
- Disconnect the suspect sensor(s) and measure reference voltage at the harness. If voltage returns to normal with sensor disconnected, the sensor is likely pulling the circuit down.
- Repair damaged wiring/connectors, clean or replace corroded terminals, and replace any failed sensor(s). Re-test voltage and clear codes.
- If wiring and sensors test good and reference remains low at the PCM, consider PCM internal fault — confirm with manufacturer diagnostics before replacing module.
- After repairs clear codes and perform a test drive/verification cycle to ensure code does not return.
Likely causes
- Short to ground or high resistance in the reference C harness
- Loose/corroded ground at PCM or chassis ground point
- Failed sensor that is loading the reference circuit
- Blown fuse or poor PCM power supply causing regulator to output low voltage
Fault status
Status
Sensor reference voltage C circuit low — PCM detected the reference supply voltage on circuit C below the expected threshold.
Repair difficulty: Medium
Diagnostic time: 0.5-3 hours
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Code
P0698
LAND ROVER
P — Powertrain
Reference voltage sensor C - low circuit
Views:
UK: 3
EN: 6
RU: 8
AI status
Completed
Completed
100%
Causes
- Poor or low battery/charging system voltage
- Blown or open fuse supplying the PCM/reference regulator
- Poor PCM power or ground connections
- Damaged, chafed or shorted wiring on reference circuit C (short to ground)
- Corroded/loose connector at sensor(s) or PCM
- Faulty sensor(s) tied to the reference circuit
Symptoms
- Malfunction indicator lamp (MIL) illuminated
- Multiple sensor-related trouble codes or erratic sensor readings
- Engine may run rough, reduced performance or stumble (depending on affected sensors)
- In some cases poor fuel economy or difficulty starting
- Some vehicle systems that rely on sensors on this reference may operate unpredictably
What to check
- Scan for additional DTCs and record freeze-frame/data PIDs to identify affected sensors
- Verify battery voltage with key ON and engine running (should be ~12.4–14.8 V)
- Inspect fuses and relays related to PCM and sensor power/reference
- Visually inspect wiring harnesses, connectors and grounds for damage/corrosion
- Back-probe the sensor reference pin at the sensor connector and at the PCM to compare voltages
- Check continuity and resistance between sensor connector reference pin and PCM reference pin
Signal parameters
- Nominal sensor reference voltage: ~5.0 V (typical acceptable range 4.75–5.25 V)
- Low condition typically flagged when reference falls below ~4.4–4.6 V (threshold varies by manufacturer)
- Open-circuit continuity: very high resistance / OL between PCM reference pin and sensor connector
- Short-to-ground: near 0 Ω between reference circuit and ground
- With key ON, engine OFF: reference should be present and stable near nominal value
Diagnostic algorithm
- Retrieve all stored DTCs and freeze-frame data. Note which sensors share reference circuit C.
- Verify battery/charging system voltage. Charge battery or repair charging if low before further testing.
- Inspect fuses, PCM power/ground connections and visible wiring for damage or corrosion; repair as needed.
- With key ON (engine OFF), back-probe the reference C pin at the PCM and at each affected sensor connector. Compare voltages; they should be within a few tenths of a volt of each other and near ~5 V.
- If reference is low at PCM pin, suspect PCM power/ground, fuse, or internal regulator. If low only at sensor connector(s), suspect wiring/connector between PCM and sensor.
- Check continuity and resistance between PCM reference pin and sensor connector. Look for high resistance or open circuit. Check for short to ground (measure resistance to ground).
- Disconnect the suspect sensor(s) and measure reference voltage at the harness. If voltage returns to normal with sensor disconnected, the sensor is likely pulling the circuit down.
- Repair damaged wiring/connectors, clean or replace corroded terminals, and replace any failed sensor(s). Re-test voltage and clear codes.
- If wiring and sensors test good and reference remains low at the PCM, consider PCM internal fault — confirm with manufacturer diagnostics before replacing module.
- After repairs clear codes and perform a test drive/verification cycle to ensure code does not return.
Likely causes
- Short to ground or high resistance in the reference C harness
- Loose/corroded ground at PCM or chassis ground point
- Failed sensor that is loading the reference circuit
- Blown fuse or poor PCM power supply causing regulator to output low voltage
Fault status
Status
Sensor reference voltage C circuit low — PCM detected the reference supply voltage on circuit C below the expected threshold.
Repair difficulty: Medium
Diagnostic time: 0.5-3 hours
Similar codes
Workshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop ManualLand Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop ManualLand Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop ManualYour experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
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