If your Toyota Camry throws a P1261 fuel injector driver circuit fault, the engine may stumble, stall at idle, or refuse to start especially after sitting overnight. This code isn’t about dirty injectors or bad fuel. It points to an electrical issue in the path between the engine control module (ECM) and one of the fuel injectors, most often the #1 cylinder injector. That means voltage, grounding, or signal integrity is compromised somewhere in the driver circuit and it’s not always obvious where.

What does P1261 mean on a Toyota Camry?

P1261 is a manufacturer-specific OBD-II code defined by Toyota as “Fuel Injector Driver Circuit Malfunction (Cylinder 1).” It triggers when the ECM detects an open or short condition in the low-side driver circuit for the #1 fuel injector the part of the system that switches the injector on and off. Unlike generic codes like P0201, P1261 is tied to Toyota’s internal monitoring of injector driver transistors and feedback signals. It doesn’t mean the injector itself is faulty, though a failed injector can cause it. More often, it’s a wiring fault, corroded connector, or failing ECM driver transistor.

When do Camry owners actually see this code?

You’ll likely notice P1261 after symptoms appear not before. Common real-world triggers include:

  • Engine cranks but won’t start, especially in cold weather
  • Rough idle or sudden stalling when stopped at a light
  • Loss of power under light acceleration (not wide-open throttle)
  • Check Engine Light illuminating with no other drivability issues until it worsens

This code sometimes appears alongside others like P0301 (cylinder 1 misfire) or P0201 (injector circuit malfunction), but P1261 is more specific: it’s telling you the ECM tried to fire injector #1 and didn’t get the expected electrical response back.

Where should you look first?

Start simple and physical not diagnostic software alone. On a Camry (especially 2012–2017 2.5L 4-cylinder models), inspect these three spots:

  1. The injector connector near the intake manifold check for bent pins, moisture, or corrosion (common if the valve cover gasket has leaked oil into the harness)
  2. The wiring harness between the injector and ECM look for chafed insulation near the firewall or sharp bracket edges
  3. The ECM ground point near the battery tray loose or corroded grounds here disrupt injector driver feedback signals

Don’t assume the ECM is bad. While possible, it’s far less common than a damaged wire or connector. A multimeter continuity test from the injector connector back to the ECM pin (with harness disconnected) usually reveals opens or shorts faster than swapping parts.

What mistakes make this worse?

Replacing the #1 fuel injector without checking wiring is the top mistake. So is clearing the code and ignoring it P1261 can progress to repeated misfires, catalytic converter damage, or even ECM failure if the short persists. Another common error: using non-OEM replacement injectors. Some aftermarket units draw different current or lack proper internal resistance, confusing Toyota’s driver circuit monitoring.

How is this different from similar P1261 codes in other cars?

P1261 means something different depending on the brand. In a GM Silverado, it refers to high-pressure fuel solenoid control. In a Subaru Outback, it points to an open circuit in the fuel delivery control module. And in a Honda Accord, it relates to direct injection timing control. So while the code number is identical, the underlying system and repair path are entirely vehicle-specific. Never apply Silverado wiring diagrams to a Camry.

Real next step: what to do tonight

Grab a flashlight and your owner’s manual. Locate the #1 fuel injector (frontmost on the 2.5L inline-4 easiest to access near the throttle body). Unplug the connector. Look for greenish corrosion on the terminals or bent pins. If it looks clean, use a multimeter to check resistance across the injector coil (should be ~12–14 ohms). Then check continuity from each pin in the connector back to the ECM specifically pins B19 and B20 on the ECM connector (2012–2017 Camry). If either line shows infinite resistance or less than 1 ohm to ground, you’ve found the fault.

For reference, Toyota’s official service documentation uses Toyota Tech Eu font name for technical illustrations and schematics.

Before you buy parts or book a shop: Verify the injector resistance, inspect the connector, and test continuity. Most P1261 cases on Camrys resolve with a cleaned connector or repaired wire not a new ECM or set of injectors.