P35AF

Cylinder 1 Injector Circuit Low

P35AF is a generic OBD-II powertrain diagnostic trouble code: Cylinder 1 Injector Circuit Low. It is logged by the engine control unit when the powertrain monitor detects that a specific fault threshold has been exceeded — typically resulting in the malfunction-indicator lamp (MIL / check-engine light) being illuminated.

Code
P35AF
Group
Powertrain
System
Powertrain
Severity
Warning (MIL on, possible limp mode)
Need P35AF disabled?
RaceTune permanently disables any OBD-II trouble code on supported ECUs — for motorsport, off-road, and export use.
→

What P35AF means

P35AF indicates that the PCM/ECM has detected an abnormally low voltage or current condition in the fuel injector control circuit for cylinder 1. The control module monitors injector driver feedback to confirm proper operation during each injection event, and a voltage reading below the expected threshold triggers this fault.

This fault most commonly results from a short circuit to ground in the injector wiring harness, a failed injector solenoid winding with reduced resistance, or a faulty injector driver stage inside the ECM. Because the cylinder 1 injector is not firing correctly, the engine may exhibit a noticeable misfire, rough idle, and elevated hydrocarbon emissions.

Diagnosis should begin with a visual inspection of the injector connector and wiring before any component replacement. Live data monitoring of injector pulse width and fuel trim values helps confirm whether the cylinder is receiving fuel. Resistance testing of the injector solenoid against the manufacturer specification is an essential step prior to condemning the ECM driver circuit.

Common causes

Most-frequently reported root causes when P35AF is logged.

  • 1
    Short circuit to ground in the cylinder 1 injector wiring harness.
  • 2
    Failed injector solenoid with resistance below specification.
  • 3
    Damaged or corroded injector electrical connector.
  • 4
    Faulty injector driver circuit inside the ECM/PCM.
  • 5
    Chafed wiring causing intermittent or permanent grounding.
  • 6
    Water intrusion into the injector connector causing tracking.
  • 7
    Incorrect injector installed with incompatible impedance.

Symptoms drivers notice

MIL illuminated with a cylinder 1 misfire or injector code stored.
Rough idle or engine misfire felt at all RPM ranges.
Increased fuel consumption due to uncontrolled fueling.
Strong fuel odour from rich-running or raw-fuel conditions.
Reduced engine power with possible limp-mode activation.

How to diagnose P35AF

A typical diagnostic flow when this code is present.

  1. 1
    Connect a scan tool, record all stored DTCs, and note freeze frame data.
  2. 2
    Inspect the cylinder 1 injector connector and wiring for visible damage, corrosion, or chafing.
  3. 3
    Measure injector solenoid resistance with a multimeter and compare to specification.
  4. 4
    Check for a short to ground on the injector signal wire using a multimeter.
  5. 5
    Monitor live injector pulse-width and short-term fuel trim data on cylinder 1.
  6. 6
    Swap the cylinder 1 injector with a known-good unit to determine if the fault follows.
  7. 7
    If wiring and injector test good, inspect ECM injector driver output before replacing the module.

Related powertrain codes

Frequently asked questions

Can I drive with P35AF active?

Short trips may be possible, but continued driving risks catalytic converter damage from unburned fuel and can worsen any underlying wiring fault. Repair promptly.

Will replacing the injector always fix P35AF?

Not always. If the root cause is a wiring short or a failed ECM driver, a new injector will not resolve the fault. Always test the circuit first.

Does P35AF always mean the injector is dead?

No. A low-circuit code indicates an electrical problem in the circuit, which could be the wiring, connector, or driver stage rather than the injector solenoid itself.

How do I tell if the ECM driver is faulty?

After confirming the injector and wiring are within specification, use a scope or a noid light to verify the ECM is producing a proper drive pulse; absence of a pulse with good wiring points to the driver.

Disabling P35AF in software

RaceTune can permanently disable P35AF — and any other OBD-II diagnostic trouble code — on every ECU family we support. The monitor is disabled inside the ECU itself, so the fault stops being logged: the warning light stays off and the engine never enters limp mode for this code. The change is tied to your exact software version.

Permanent
The monitor is disabled in the ECU itself — not just cleared. It cannot return.
Tailored to your file
Each patch is matched to your specific software version — never a one-size-fits-all file.
Reversible
The original file is always preserved. Reflash the stock to return the ECU to factory state.

Software modifications affect emissions compliance and are not road-legal in many jurisdictions. RaceTune service files are intended for motorsport, off-road, and export use.

Got P35AF in your scan?

Upload your ECU file — we'll identify the exact software version and confirm whether a disable is available for your car.

Upload your file