DTC 122 — Intake Manifold Absolute Pressure Signal Out of Range – Low — International DT466E
DTC 122 on International DT466E (1996–2003) indicates the MAP/boost sensor signal voltage is below its valid range. The engine may run with low power.…
What it means
Navistar three-digit code 122: Intake Manifold Absolute Pressure Signal Out of Range – Low. Generic definition: MAP (boost) sensor signal voltage is below its valid range. Typical on this platform: usually an open or shorted MAP sensor circuit or a failed sensor; expect low power.1
Most likely causes
- MAP sensor internal failure causing low output voltage — A failed MAP sensor can pull the signal low, setting 122.1
- Open or high-resistance in MAP signal wire to ECM — An open signal circuit drives the ECM input low.1
- MAP sensor ground or 5 V reference open/shorted — Loss of reference or ground biases the sensor output low.1
- Connector corrosion/moisture at MAP sensor — Corrosion increases resistance and can pull the signal low.1
How to diagnose
- Verify code 122 is present with a scan tool or flash codes; confirm no other active codes. Navistar three-digit DTCs, read by counting flashes of the amber engine lamp or with a scan tool.
- Inspect MAP sensor connector for corrosion, moisture, bent pins, and secure lock.
- Check MAP sensor wiring harness for chafing, pinching, or opens between sensor and ECM.
- With key on engine off, check MAP sensor 5 V reference and ground at the sensor connector; repair opens/shorts as needed.
- Backprobe MAP signal at the sensor and at the ECM; compare voltage. A signal that is low at the sensor points to sensor failure; low only at ECM points to wiring.
- If reference/ground and wiring are good, substitute a known-good MAP sensor and recheck code and signal.
Parts and tools you may need
- Digital multimeter
- Scan tool capable of Navistar three-digit codes
- Contact cleaner
- Basic hand tools
Tools you’ll need
- OBD-II scan tool — Reads Navistar three-digit code 122 and monitors live MAP voltage to confirm low signal.
- Digital multimeter — Checks 5 V reference, ground continuity, and MAP signal voltage at sensor and ECM to isolate wiring vs sensor fault.
- Terminal release tool set — Safely opens MAP sensor connector to inspect pins and test continuity without damage.
- Inspection mirror and flashlight — Reveals hidden chafing or moisture at MAP sensor and harness routing on DT466E.
Rough cost and difficulty
| Likely repair | Parts | Shop labor | Who usually does it |
|---|---|---|---|
| Wiring or connector repair | $10–$100 | 1–4 hrs | DIY with tools and a manual |
| MAP/boost pressure sensor | $40–$200 | 0.3–1 hrs | Easy DIY |
Typical US independent-shop figures; labor runs about $140–$200 per hour (dealers charge more). Confirm the diagnosis before buying parts.
When to see a pro
If wiring tests are inconclusive, ECM input is suspect, or the code returns after sensor replacement, have a qualified diesel technician perform pin-to-pin continuity and ECM input tests. Do not attempt diagnosis of high-pressure oil injection systems. This guide is diagnostic only.
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
Spotted an error, or something missing? Tell us
Run a International DT466E? This goes straight to the editor — it is not published.