P1264: High to Low Side Short in Cylinder #4 Injector Circuit
The P1264 code indicates a short circuit between the high side and low side of the fuel injector circuit for cylinder #4. This typically means the injector coil has failed internally, causing a direct short between the power and ground wires. This can result in a no-start condition, misfire, or engine running poorly. The short may also blow the injector fuse or damage the engine control module (ECM).
1. Symptoms You Will Notice
- Check Engine Light on
- Engine misfire on cylinder #4
- Rough idle or hesitation
- Possible no-start condition if injector fuse blows
2. Most Common Causes
- Faulty immobilizer module (PATS)
- Faulty powertrain control module (PCM)
- Damaged wiring or connectors between the immobilizer and PCM
- Unprogrammed or damaged keys
- Blown fuses related to the security system
- Electromagnetic interference in the communication wiring
3. Step-by-Step Diagnosis
Step 1: Scan for codes and record freeze frame data.
Step 2: Visually inspect injector #4 connector and wiring for damage.
Step 3: Measure resistance across injector #4 terminals; compare to specification (typically 12-16 ohms). A short will show near 0 ohms.
Step 4: Check for continuity between injector high side and ground; if present, injector is shorted.
Step 5: Swap injector #4 with another cylinder and see if code moves; if so, replace injector.
Step 6: If wiring is damaged, repair or replace harness section.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
No, driving with a shorted injector can cause further damage to the ECM or blow fuses, potentially leaving you stranded. It's best to have it repaired immediately.
How much does it cost to fix?▼
Replacing a single fuel injector typically costs $150-$400 including parts and labor. If wiring repair is needed, costs may be higher.
5. Commonly Affected Makes
This is a manufacturer-specific code. The exact manufacturer is not confirmed in our current database.