Low fuel pressure from a weak fuel pump, clogged fuel filter or failing pressure regulator; Vacuum leak or unmetered air leak after the airflow measurement (split hoses, intake manifold gasket, loose intake duct); Restricted or faulty fuel injectors delivering too little fuel; Faulty or contaminated MAP sensor, or a fault in the mass airflow measurement, giving wrong load readings; Ageing or slow oxygen sensor giving a false lean reading; Exhaust leak upstream of the oxygen sensor drawing in air; Wiring or connector fault on the fuel pump, injector or sensor circuits.

P1298

Lean Operation At Wide Open Throttle.

Plymouth
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
2: AreaFuel and air metering (injector circuit)
98: FaultThe specific fault in that area

What it means

On Plymouth models P1298 means the powertrain control module detected a lean air-fuel mixture while the throttle was at or near wide open. The PCM normally enriches the mixture at full load, so when the oxygen sensor signals stay lean during that enrichment it logs this code. It points to fuel delivery that cannot keep up with demand, or unmetered air entering the engine.

Symptoms

Malfunction indicator lamp on
Hesitation, stumble or flat spot under full throttle
Loss of power at high load or when accelerating hard
Surging or poor performance when overtaking or climbing hills
Possible pinging or knocking under load
Poor fuel economy

Possible causes

Low fuel pressure from a weak fuel pump, clogged fuel filter or failing pressure regulatorlikely
Vacuum leak or unmetered air leak after the airflow measurement (split hoses, intake manifold gasket, loose intake duct)likely
Restricted or faulty fuel injectors delivering too little fuelpossible
Faulty or contaminated MAP sensor, or a fault in the mass airflow measurement, giving wrong load readingspossible
Ageing or slow oxygen sensor giving a false lean readingpossible
Exhaust leak upstream of the oxygen sensor drawing in airpossible
Wiring or connector fault on the fuel pump, injector or sensor circuitsrare

How to diagnose

Read all stored and pending codes and the freeze frame data, noting engine load, speed and fuel trim values when the code set
Check for other fuel trim, misfire or sensor codes that point to a more specific fault
Visually inspect vacuum hoses, intake ducting, manifold connections and the exhaust upstream of the oxygen sensor for leaks or damage
Inspect the wiring and connectors to the oxygen sensors, MAP sensor, injectors and fuel pump for damage, corrosion or looseness
Watch live fuel trims and oxygen sensor readings at idle and under load to see whether the lean condition appears only at high demand
Test fuel pressure and volume against the manufacturer's specification, including under load; the figures vary by engine and model
Check MAP sensor and airflow readings against expected values, and test for a smoke-detectable intake leak
Test injector resistance and spray pattern or flow, and check the oxygen sensor response if everything else is sound

How to fix

Replace the fuel filter, fuel pump or pressure regulator if pressure or volume is below specification
Repair or replace leaking vacuum hoses, intake gaskets or loose ducting
Clean or replace faulty fuel injectors
Replace a faulty MAP sensor or airflow-related sensor that is giving incorrect readings
Replace a failed oxygen sensor or repair any exhaust leak ahead of it
Repair damaged wiring or connectors found in the affected circuits

Can I keep driving?

Medium severity

The car can usually be driven gently for a short time, but avoid heavy throttle because a sustained lean mixture at full load can cause overheating and engine damage. Get it diagnosed soon.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.