What P1495 means
P1495: NOx sensor circuit — signal voltage low (equivalent SPN 3216 FMI 4).
Applies to: PACCAR MX-11, MX-13, 2013–2026 (Kenworth & Peterbilt).
Severity: High — MX derate schedules are aggressive.
Symptoms you'll see
- MIL
- Dash DEF/SCR warning
- DAVIE4 shows native P1495 alongside SPN/FMI
Likely causes (ranked by probability)
- Failed NOx sensor (~60%)
- Harness damage (~25%)
- Connector corrosion (~10%)
- ECU fault (~5%)
Diagnostic steps
- Read in DAVIE4 — note accompanying codes; MX platforms escalate quickly.
- Inspect sensor and harness; run DAVIE4's NOx plausibility check.
- Replace sensor, clear, complete the aftertreatment verification in DAVIE4.
Tools that read, clear and verify this code
DAVIE4 guided sequence; CV scanners read and clear. For the full per-platform picture see the PACCAR MX-13 fault codes page and our Aftertreatment fault codes.
Frequently Asked Questions
Can I drive with P1495 active?
Severity on this code: High — MX derate schedules are aggressive. If a derate countdown is armed, use the remaining runtime to reach a shop — not to finish the week. Verify the root cause with the diagnostic steps above rather than clearing and hoping.
Will clearing P1495 without repairs work?
The code will return — usually within one drive cycle — and on aftertreatment-related faults the inducement countdown often shortens each time. Repair first, verify with the guided test, then clear.
Which scanner reads P1495?
DAVIE4 guided sequence; CV scanners read and clear.