P1204 Code: Meaning, Symptoms, Causes & Fix

Overview

Code P1204 indicates a fault in Injector Circuit Open / Shorted - Cylinder #4, typically within fuel delivery and pressure control.

Symptoms

reduced fuel economy
hesitation under acceleration
engine may stall at idle

Common causes

Open circuit in wiring affecting injector circuit open / shorted - cylinder #4
Broken terminal inside harness
Connector pin damage/corrosion or harness stress near related components

How to diagnose P1204

Confirm P1204 and capture freeze-frame data with a professional scan tool.
Inspect wiring, connectors, and grounds related to injector circuit open / shorted - cylinder #4 for obvious defects.
Use a continuity test from module pin to component to identify opens/high resistance.
Check for related DTCs to identify the root-cause chain before replacing parts.
After repair, clear codes and confirm readiness monitors complete without recurrence.

Severity of code P1204

Moderate: This code is moderate severity: the vehicle may still operate, but fault progression can increase repair cost over time.

Can you drive with P1204?

Most vehicles can be driven short-term with P1204, but postpone heavy load/highway driving until repaired.

If the warning lamp is flashing or drivability/safety is affected, avoid driving and diagnose immediately.

How to fix it (step-by-step)

Repair obvious wiring/connector faults first to prevent repeat parts replacement.
Address the root fault mode (open) in the injector circuit open / shorted - cylinder #4 circuit/system.
Apply the required relearn/adaptation procedure if specified by service information.
Road-test and verify P1204 remains cleared under the conditions that originally set the code.

Fix options

Restore continuity and verify pin tension.
Repair open circuit and secure connector lock.
Clear DTCs and verify with live data and completed drive cycle.

Typical repair cost

$220-$1100

Common mistakes when diagnosing P1204

Replacing parts without verifying voltage, ground, and signal integrity first.
Ignoring related stored/pending codes that indicate upstream faults.
Skipping post-repair verification drive cycle and readiness checks.

P1204 in common vehicles

P1204 appears across makes such as Mazda, Subaru, Lexus, Jeep. Failure patterns differ by platform: wiring routes, software calibration, and component supplier revisions can change root cause.

Frequently asked questions

What causes P1204?

P1204 is commonly set by open faults affecting injector circuit open / shorted - cylinder #4.

How much does it cost to fix P1204?

For P1204, repair costs are typically $220-$1100 depending on exact root cause, labor rates, and part quality.

Can I clear P1204 without repair?

You can clear P1204 temporarily, but the code usually returns until the underlying fault is corrected.