276
g/auto • Posted by u/wrench_monkey •

2019 Kenworth T680 Cummins X15 — intermittent no-start, P0340 and P0345

Fleet truck, 340,000 miles on the X15. Intermittent no-start, happens 1 in 20 attempts. Cranks fine but won't fire.

Codes: P0340 (CMP sensor A, Bank 1, low input) and P0345 (CMP sensor A, Bank 2).

Replaced both CMP sensors with OEM Cummins sensors. Issue persists.

Is this a wiring/connector issue? ECM? I've never had cam sensor codes on an X15 that weren't fixed by replacing the sensors.

💬 4 replies

Log in or sign up to leave a reply.

u/road_warrior_rex •

How much does the reluctor wheel replacement run on an X15? That sounds like a day job.

121
u/scan_tool_sam •

InPower or Cummins INSITE will show you the actual CMP sensor signal quality, not just the fault code. Connect during a no-start event and look at signal amplitude and frequency. If the reluctor wheel is the issue, you'll see it in the raw data. Also check for active SPN codes alongside the P codes — sometimes the real fault is hiding.

89
u/diesel_dan •

Pull the ECM connector first. Kenworth cab moisture issues are well-documented, and the ECM connector sees condensation on humid nights. Clean with electrical contact cleaner, apply dielectric grease, reseat firmly. I've fixed three "no-start" issues on T680s this way after everything else checked out.

64
u/admin_jake ADMIN •

When both CMP codes appear together and don't resolve with sensor replacement on an X15, the most common culprits are: (1) cam reluctor wheel — 60-tooth, check for damaged or worn teeth, or if the wheel has shifted; (2) cam sensor harness chafing point at the back of the block — common failure on high-mileage X15s. Get a scope on both sensors during a crank event and compare waveforms. A missing tooth or erratic signal pattern will be obvious.

52