P218E

Code

Generic P — Powertrain

Throttle/Fuel Inhibit B Circuit High

Brand: Generic

Type: P — Powertrain

Views: UK: 21 EN: 38 RU: 20

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Page language: EN

Causes

Open or disconnected wiring in the Throttle/Fuel Inhibit B circuit
Short to battery (intermittent or permanent) on the inhibit circuit
Corroded or damaged connector or terminal
Faulty throttle/fuel inhibit switch or sensor
Poor or missing ground or reference voltage to the circuit
PCM or module internal fault

Symptoms

Malfunction Indicator Lamp (MIL) illuminated
Reduced engine power or limp-home mode (throttle or fuel limited)
Poor or no throttle response
Intermittent loss of driveability or stalling
Stored DTC(s) and possible related codes

What to check

Retrieve freeze frame and any related stored codes
Visually inspect wiring, connectors, and harness routing for the inhibit circuit
Check fuses and relays powering the circuit and PCM
Backprobe inhibit signal with key ON (engine OFF) and measure voltage vs. ground
Check reference voltage and ground continuity at switch and PCM
Wiggle harness while monitoring signal for intermittent changes

Signal parameters

Expected signal voltage: nominal 0–5.0 V digital/logic circuit (manufacturer-specific threshold). High fault typically seen when >~4.5 V or near battery voltage.
Reference/logic supply typically ~5 V from PCM (verify vehicle-specific)
Switch/logic low when active: near 0 V; inactive or open may float to pull-up voltage (~5 V)
Ground continuity: near 0 Ω between sensor ground and PCM ground

Diagnostic algorithm

Read DTC(s) and freeze-frame data; note conditions when fault set (key on, engine rpm, temp).
Visually inspect harness, connectors and terminals for corrosion, damage, or disconnection at the throttle/fuel inhibit switch and PCM. Repair any obvious damage.
With KEY ON ENGINE OFF, backprobe the inhibit signal wire at the switch connector and at the PCM. Measure voltage to ground. Verify reference voltage and ground are present.
If signal is high (~battery or >4.5 V) at switch connector, disconnect the switch and re-measure. If voltage remains high with switch disconnected, suspect wiring short to battery or pull-up inside PCM.
Check continuity between inhibit signal pin at switch and PCM pin. Look for open circuits or high resistance. Wiggle harness to check intermittent faults.
If signal is low or behaves correctly at PCM but high at the switch, replace the switch or repair connector/wiring as needed.
If wiring checks good and signal at PCM remains high, perform bench or harness isolation tests; consider PCM input fault—confirm with manufacturer procedures before PCM replacement.
After repairs, clear codes and perform test drive to confirm fault does not return. Monitor live data while replicating conditions that set the code.

Likely causes

Connector corrosion or bent terminal at inhibit switch or PCM
Wiring chafe that contacts battery voltage or accessory feed
Failed inhibit switch (contacts stuck open/high impedance)
Damaged insulation resulting in intermittent short to battery
Faulty PCM input stage (less common)

Fault status

⚠️ Status

Throttle/Fuel Inhibit B Circuit High — inhibit input voltage above threshold; possible open, short to battery, faulty switch/connector, or PCM input fault.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours