Faulty fuel injector number 7 with an internally intermittent coil or winding; Damaged or chafed wiring in the injector 7 circuit, often where the harness bends near the engine; Corroded, loose, or backed-out terminals at the injector 7 connector or at the PCM connector; Water or oil intrusion into the injector 7 electrical connector causing intermittent shorts; PCM driver circuit for injector 7 failing intermittently (rare but possible); Aftermarket or damaged injector pigtail that does not maintain a solid connection

DTC codes / Chrysler codes / P1240

P1240 · ChryslerInjector Circuit Cylinder 7 Intermittent

Q: What does code P1240 mean?

Injector Circuit Cylinder 7 Intermittent. P1240 on a Chrysler vehicle means the powertrain control module (PCM) has detected an intermittent fault in the electrical circuit for fuel injector number 7. The PCM monitors injector current and voltage; when the signal momentarily drops out or spikes outside the expected range, it stores this code because the problem is not constant.

P1240 on a Chrysler vehicle means the powertrain control module (PCM) has detected an intermittent fault in the electrical circuit for fuel injector number 7. The PCM monitors injector current and voltage; when the signal momentarily drops out or spikes outside the expected range, it stores this code because the problem is not constant.

SystemPowertrain

Code typeChrysler specific

SeverityMedium

Fix difficultyIntermediate

AreaFuel and air metering (injector circuits)

Symptoms you may notice

Check engine light (malfunction indicator lamp) illuminated, often with no other noticeable symptoms
Intermittent engine misfire or rough running, especially under load or at certain RPMs
Slight loss of power or hesitation during acceleration
Occasional shaking or vibration felt through the steering wheel or seat
Poor fuel economy if the injector stops firing for short periods
In rare cases, a flashing check engine light if the misfire becomes severe enough to damage the catalytic converter

Common causes, most likely first

Faulty fuel injector number 7 with an internally intermittent coil or winding
Damaged or chafed wiring in the injector 7 circuit, often where the harness bends near the engine
Corroded, loose, or backed-out terminals at the injector 7 connector or at the PCM connector
Water or oil intrusion into the injector 7 electrical connector causing intermittent shorts
PCM driver circuit for injector 7 failing intermittently (rare but possible)
Aftermarket or damaged injector pigtail that does not maintain a solid connection

How to diagnose and fix it

Inspect the injector 7 connector and wiring for corrosion, chafing, or loose pins; clean or repair as needed
Perform a wiggle test on the injector 7 harness while the engine is running to reproduce the intermittent fault
Swap injector 7 with a known-good injector from another cylinder (if accessible) and see if the code moves
Measure resistance of injector 7 with a multimeter and compare to the other injectors; look for an open or shorted winding
Use a noid light or oscilloscope to check for consistent injector pulse at the injector 7 connector
Check for technical service bulletins (TSBs) or software updates for the PCM that address injector circuit faults
If all external checks pass, diagnose the PCM driver circuit or replace the PCM as a last resort

Intermittent injector faults that fool technicians

A common mistake is replacing the injector immediately, but the fault often lies in the connector or harness, especially where the wiring rubs against the engine cover or intake manifold.
The code can set from a momentary glitch that lasts less than a second, so the injector may test perfectly fine with a multimeter when the engine is cold or idling.
Chrysler engines in certain models (e.g., 3.6L Pentastar V6) are known for injector connector issues due to heat and vibration, so always inspect the connector before condemning the injector.
A failing spark plug or ignition coil on cylinder 7 can cause a misfire that the PCM may misinterpret as an injector circuit fault, so check secondary ignition components as well.
If the injector circuit is intermittent, the PCM may not set a misfire code immediately; P1240 can be the only clue until the problem worsens.

Can I keep driving with P1240?

You can usually drive short distances at moderate speeds, but avoid heavy acceleration or towing because an intermittent misfire can overheat the catalytic converter. If the check engine light starts flashing, pull over and stop driving to prevent costly damage.

Tools that help

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Guidance is general and written for Chrysler vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.