OBD-II Code P0283 — What It Means & How to Fix It

What Does This Error Mean?

P0283 means the fuel injector circuit for Cylinder 8 is reading a high voltage or current signal. The ECM controls injectors by switching a ground circuit on and off. When Cylinder 8's circuit reads higher than expected, it points to a short to voltage or an injector that's drawing excessive current. A high-circuit condition can cause the injector to fire too long or not shut off, flooding Cylinder 8 with fuel. Symptoms include strong fuel smell, rough running, black exhaust smoke, and often a Cylinder 8 misfire code.

Affected Models

All vehicles 1996+ with 8 or more cylinders
Common in V8, V10, and V12 engines
Common in vehicles with damaged rear-bank injector wiring
More frequent after improper injector wiring repairs

Common Causes

Short to voltage in the Cylinder 8 injector control wire
Internally shorted Cylinder 8 injector drawing excessive current
Wiring harness damage where the Cylinder 8 control wire contacts a 12V source near the firewall
Wrong-spec injector installed with lower resistance than the circuit is designed for
ECM internal driver failure for Cylinder 8 stuck in a continuous high-output state

How to Fix It

Inspect the Cylinder 8 injector harness from the connector all the way back toward the ECM. On V8 engines, Cylinder 8 wiring runs along the driver-side bank — look for bare wires touching battery cables, firewall power feeds, or alternator wiring.

The area near the firewall is a common location for wiring shorts to power — multiple harnesses converge here and can rub against each other.
With the Cylinder 8 injector unplugged and the key ON (engine off), check the voltage on the control wire terminal at the harness connector. This terminal should read near zero volts. A 12V reading confirms the control wire is shorted to a power source.

If the control wire reads 12V, wiggle the harness while watching the meter — sometimes the short is intermittent and will appear during movement.
Measure the Cylinder 8 injector resistance by probing its two terminals directly. Normal is 10–18 ohms. A reading very close to zero indicates an internal short — the injector will draw maximum current whenever power is applied and must be replaced immediately.

A near-zero resistance injector can overheat and damage the ECM driver circuit if left installed and operated.
Verify injector specifications if recent injector work was performed. A low-impedance injector (designed for high-performance applications) installed in a standard high-impedance circuit draws far more current than the ECM expects, triggering a high-circuit code.

The correct OEM injector part number for your vehicle ensures the right resistance specification every time.
If wiring and the injector both test normal, have a professional verify the ECM's Cylinder 8 driver output using a lab scope. Confirm the ECM is actually at fault before any replacement — driver circuit failures inside an ECM are real but relatively uncommon compared to wiring and connector problems.

Request that the technician document their findings before proceeding with ECM replacement.

When to Call a Professional

A high-circuit fault that causes the Cylinder 8 injector to stay on will continuously flood that cylinder with fuel. This washes oil off cylinder walls, ruins oxygen sensors, and will quickly destroy the catalytic converter. If you notice a strong raw fuel smell from the exhaust or black exhaust smoke at idle, stop driving and have the vehicle inspected immediately.

Frequently Asked Questions

What is the difference between P0282 and P0283?

Both codes are about Cylinder 8's injector circuit. P0282 is a LOW circuit reading — typically a broken wire, bad connector, or open injector. P0283 is a HIGH circuit reading — typically a short to voltage or a shorted injector. Diagnosis is different for each, even though both affect the same cylinder.

How do I know if my Cylinder 8 injector is stuck open?

Signs of a stuck-open injector include: a strong fuel smell from the exhaust at idle, black or dark grey smoke from the tailpipe, poor idle quality on the affected cylinder side, and rapid oxygen sensor degradation. If you suspect it, don't drive — have it inspected promptly.

How much does it cost to fix P0283?

Wiring repair: $100–$300. Injector replacement: $150–$400 installed. ECM repair or replacement: $300–$1,200+.