P0236 — Turbocharger/Supercharger Boost Sensor A Circuit Range/Performance — 7.3 Power Stroke

Diagnostic reference for 7.3L Power Stroke (1999–2003) P0236.

Updated October 15, 2026

What it means

Generic definition: The boost (MAP) sensor signal is implausible for the operating conditions. On the 7.3L this is usually the MAP sensor hose (cracked, plugged with oil/soot or loose) or a failing MAP sensor; check the hose and compare MAP with barometric pressure key-on, engine off.¹

Most likely causes

1. MAP sensor signal hose cracked, plugged with oil/soot, or loose — The 7.3L MAP sensor reads boost through a small hose from the intake. A cracked, plugged or disconnected hose, or an unplugged/corroded connector, can make the signal implausible.¹²
2. Failing MAP sensor — A degraded MAP sensor can produce a signal outside the expected range for operating conditions.¹³
3. Signal wiring issue affecting MAP voltage — Wiring faults can move the MAP signal out of range. A short to 5 V reference can drive the signal high; other wiring faults can make it low or erratic.³²

How to diagnose

1. Verify the code is present and note freeze-frame conditions (engine speed, load, MAP reading).
2. Key-on, engine off: compare MAP sensor reading to barometric pressure; a large deviation suggests a sensor or hose fault.
3. Inspect the MAP sensor hose from the intake to the sensor for cracks, oil/soot plugging, kinks, or looseness; replace or clean as needed.
4. Inspect the MAP sensor electrical connector for corrosion, oil intrusion, or loose terminals; repair connector integrity.
5. With a scan tool, monitor live MAP voltage/signal at idle and under steady load; look for implausible jumps or a signal that does not track with boost.
6. If the hose and connector are good, compare MAP sensor output to a known-good sensor or substitute test to isolate a failing sensor.

Common mistake to avoid

Replacing the turbo before smoke-testing the intake. Boost leaks at intercooler boots, end tanks and clamps are a common cause of low power and underboost codes, and they mimic a failing turbo. Source: BD Diesel — 6.7L Power Stroke problems and real fixes.

Parts and tools you may need

• Scan tool with live data
• Multimeter
• MAP sensor vacuum hose
• Replacement MAP sensor (if testing confirms failure)

Tools you’ll need

• OBD-II scan tool — Reads P0236 and freeze-frame data, and monitors live MAP voltage/signal vs boost to detect implausible readings.
• Digital multimeter — Checks MAP sensor supply, ground, and signal voltage key-on engine-off against barometric pressure and under load.
• Inspection mirror — Lets you see the MAP sensor hose routing and connections on the 7.3L intake for cracks, oil/soot plugging, kinks, or looseness.
• Hand vacuum pump with gauge — Applies controlled vacuum to the MAP sensor hose to verify the sensor tracks pressure and the hose is not leaking or plugged.

Rough cost and difficulty

Typical US independent-shop figures; labor runs about $120–$180 per hour (dealers charge more). Confirm the diagnosis before buying parts.

When to see a pro

If the MAP signal remains implausible after hose/connector service and sensor substitution, have a diesel technician check PCM inputs and wiring integrity. Do not attempt high-pressure oil system service. If the vehicle shows low power, surging, or hard start, also evaluate ICP/IPR and related HEUI systems.

Check for recalls

Recalls are tied to your truck’s VIN, so check yours directly: enter the VIN at NHTSA’s recall lookup. Open safety recalls are repaired free at a dealer.

Sources