P1247 — Sensor Power Supply High Input

Will P1247 clear itself?

Sometimes P1247 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

Is it safe to drive with P1247?

In most cases the car remains drivable, possibly with reduced performance or a disabled auxiliary system. If symptoms include stalling, no-start or brake/steering warnings, treat it as urgent.

How do I diagnose P1247 myself?

Start with a scan: confirm P1247, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the sensor power supply, and verify the suspect component against live data before buying parts.

How much does it cost to fix P1247?

Replace the faulty sensor or actuator — $150–$500; Repair wiring or connectors — $80–$250; Control module repair — $300–$1,000. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What are the symptoms of P1247?

Drivers most often notice: Check Engine Light on, increased fuel consumption in some cases, the affected system operates intermittently or not at all, possible limp mode depending on the affected component.

When your scan tool pulls code P1247, the engine control unit is telling you it has detected a problem with a sensor power supply circuit — specifically, the voltage on that circuit is running higher than it should. This puts P1247 squarely in the powertrain fault family, affecting either engine management or transmission-related sensors depending on your vehicle.

The phrase "circuit high" means exactly what it sounds like: instead of seeing the expected regulated reference voltage (usually somewhere in the 5-volt range for most sensors), the module is reading something much closer to battery voltage — 12 volts or more. This typically happens one of three ways: a power wire has found its way into the signal circuit somewhere, a ground path has opened up and the circuit is picking up stray voltage, or the sensor itself has failed in a way that pulls the signal line high. The ECU won't trigger this light off a single bad reading. It needs to see the condition persist under specific driving conditions before lighting up the dashboard.

That persistence is actually useful diagnostic information. When P1247 sets, the ECU stores freeze frame data — a snapshot of engine load, RPM, coolant temperature, and vehicle speed at the exact moment the fault occurred. That snapshot tells you what conditions to reproduce when you start testing, which saves plenty of wandering around under the hood chasing ghosts.

Symptoms

• Check Engine Light illuminated on the dashboard
• Noticeable increase in fuel consumption during normal driving
• The affected sensor system operates intermittently or stops working entirely
• Reduced engine performance or limp-home mode activation in some vehicles
• Possible triggering of related trouble codes in severe cases

Causes

• Broken or disconnected ground wire in the sensor power supply circuit
• Signal wire accidentally shorted to a 12-volt power source
• Sensor or actuator internally failed and feeding high voltage back into the circuit
• Corroded, loose, or physically damaged connector at the sensor or ECU
• Faulty output driver inside the control module itself
• Wiring harness damage creating an internal short or open circuit
• Complete failure of the sensor or actuator powered by that supply circuit

How to Diagnose

1. Plug in your OBD2 scanner and confirm P1247 is an active or pending code. Record the freeze frame data — that information is your roadmap for recreating the fault condition.
2. Check for any other stored codes at the same time. Related codes frequently point to the actual root cause rather than just the symptom. Pull up any available TSBs for your specific make, model, and year; manufacturers sometimes release software updates or known-fix bulletins that can resolve these issues without mechanical work.
3. Get your hands on the wiring harness feeding the affected circuit. Look for rubbed-through insulation, connector pins pushed out of position, corrosion buildup, or anything that looks like it has been cooking near heat sources.
4. With the sensor unplugged from its connector, check voltage at the harness side. If you still see battery-level voltage on that wire with the sensor disconnected, you have a short to power somewhere in the wiring itself. If the voltage drops back to normal, the sensor is the culprit.
5. Test reference voltage, ground integrity, and signal continuity directly at the component connector while it is unplugged from the harness.
6. Perform a wiggle test on the harness while monitoring live data. Any signal dropout or fluctuation during physical manipulation points to a broken wire inside the insulation that is making partial contact.
7. Once repairs are made, clear the code and run a complete drive cycle — including the conditions captured in the freeze frame — to verify P1247 does not return.

Repair Options

Sensor or actuator replacement — When the component itself has failed and is feeding high voltage back into the circuit, replacement is the fix. Parts and labor run roughly $150 to $500 depending on the vehicle and part cost.

Wiring or connector repair — Broken wires, corroded pins, and damaged connectors are the most common culprits behind this code. Repairing or replacing the affected harness section or connector typically costs $80 to $250.

Control module repair — If the fault traces back to the ECU output driver, the module itself may need attention. This can involve module repair, reprogramming, or in rare cases replacement, running $300 to $1,000.

Total Cost

P1247 repair costs fall between $80 and $1,000 depending entirely on which link in the chain has failed. Most of the time you are looking at a wiring issue or a single failed sensor — the less expensive scenarios. Always confirm the exact source of the problem before spending money on a control module, which is the most expensive and least common cause.

Can You Drive with P1247?

Severity level: short. Most vehicles remain drivable with this code present, though you may notice higher fuel consumption or reduced performance. If the malfunction causes stalling, prevents starting, or triggers warnings for brakes or steering, stop driving and address it immediately. Otherwise, schedule repair at your earliest convenience.