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DTC codes / P26xx · Computer and output circuits / P262E

P262ESensor Reference Voltage G Circuit High

P262E indicates that the powertrain control module (PCM) has detected an abnormally high voltage on the sensor reference voltage G circuit, which is a regulated 5-volt supply used by one or more sensors. The PCM monitors this circuit and sets the code when the voltage exceeds the expected upper limit, typically due to a short to voltage or an open circuit that causes the reference line to float high.

SystemPowertrain
Code typeGeneric (all makes)
SeverityMedium
Fix difficultyIntermediate
AreaComputer and output circuits

Symptoms you may notice

  • Illumination of the check engine light (malfunction indicator lamp, MIL)
  • Often no symptoms besides the warning light, especially if the affected sensor is not critical to driveability
  • Rough engine idle or poor performance if the sensor on circuit G is used for fuel or air control
  • Incorrect readings on the dashboard gauge for a related system such as fuel level or temperature
  • Reduced fuel economy or increased emissions if the sensor signal is skewed
  • Intermittent stalling or hesitation if the reference voltage intermittently goes high

Common causes, most likely first

  1. Short to voltage on the reference voltage G circuit, often due to chafed wiring contacting a 12-volt source
  2. Open circuit in the reference voltage G wire, causing the PCM to see a high voltage on the sense line
  3. Faulty sensor connected to the reference voltage G circuit, internally shorted and pulling the voltage high
  4. Corroded or damaged connector pins at the sensor or PCM, creating high resistance or intermittent contact
  5. PCM internal fault, though this is less common and should be confirmed after other causes are ruled out
  6. Water intrusion into a connector or wiring harness, leading to corrosion and voltage irregularities

How to diagnose and fix it

  1. Use a scan tool to retrieve all stored codes and freeze-frame data, then clear codes and test-drive to see if P262E returns
  2. Visually inspect the wiring harness and connectors for the sensor(s) on the reference voltage G circuit for damage, corrosion, or loose pins
  3. Measure the reference voltage at the sensor connector with a digital multimeter (DMM) with the key on and engine off; compare to the specified 5 volts
  4. Disconnect the sensor and check for a short to voltage or open on the reference voltage G wire using a wiring diagram and DMM
  5. Check for continuity and resistance on the ground circuit for the sensor, as a poor ground can cause a high reference voltage reading
  6. If the wiring and connectors are good, substitute a known-good sensor of the same type and recheck the voltage
  7. If all else fails, diagnose the PCM by checking its power and ground supplies and consider replacement only after confirming no other faults

Reference voltage G circuit pitfalls

  • A common mistake is to replace the sensor first, but the reference voltage G circuit is shared by multiple sensors, so a short in one sensor can affect all sensors on that circuit.
  • The code can set intermittently due to a wiring harness that rubs against a metal component, so wiggle-testing the harness while monitoring voltage is crucial.
  • Some vehicles use the reference voltage G circuit for the accelerator pedal position sensor, so a fault here can cause reduced power mode even if the engine seems fine.
  • A high voltage on the reference circuit can be caused by a faulty alternator or voltage regulator feeding excessive voltage into the electrical system, so check charging system voltage.
  • Do not overlook aftermarket accessories wired into the reference circuit, such as piggyback tuners or alarm systems, which can backfeed voltage and set this code.

Can I keep driving with P262E?

It is generally safe to drive with P262E if the vehicle runs normally, but avoid aggressive acceleration or towing until the fault is repaired. If the engine runs poorly, stalls, or enters reduced power mode, limit driving to a short distance to a repair shop.

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.

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