Injection Actuation Pressure Above Normal
The CAT-CID164-FMI0 (Caterpillar) diesel fault code means: Injection Actuation Pressure Above Normal. This is a serious severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- advanced
- Estimated cost
- $400-$3500
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Common Symptoms
- Engine will not start or cranks with no fire
- Hard start when hot
- Black smoke
- ECM forces engine derate
Probable Causes (Ranked by Likelihood)
- IAPR stuck closed, holding pressure too high Likely
- Injection actuation pressure sensor reading wrong Likely
- High-pressure oil pump internal failure Possible
Frequently Asked Questions
What does CAT code CID164-FMI0 mean?
CAT code CID164-FMI0 (Injection Actuation Pressure Above Normal) is a serious-severity fault in the HEUI injection system. HEUI injection actuation pressure too high. IAPR may be stuck closed or sensor is reading wrong. HEUI (Hydraulically actuated Electronically controlled Unit Injectors) uses high-pressure engine oil to fire injectors, so HEUI faults often trace to oil pump wear, oil leaks, or sensor failures.
Can I drive with CAT CID164-FMI0?
No. HEUI faults typically cause hard start, no-start, or derate. Continued driving risks stranding. Tow to a CAT-capable shop.
How much does it cost to fix CAT CID164-FMI0?
Typical cost is $400-$3500. Sensor or IAPR replacement is at the low end; high-pressure oil pump or injector work is at the high end and usually requires CAT dealer-level diagnostic time.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
Connect CAT ET and confirm the active fault; note HEUI actuation pressure live value.
Inspect IAPR connector and wiring at front of engine for damage.
Measure HEUI actuation pressure with CAT ET during cranking; spec ~870 psi at cranking for start.
If pressure is low at cranking, test HP oil pump and check injector cup seals for oil loss.
Replace sensor, IAPR, or pump as indicated by tests.
Sources 1
This page is built from documented references. Verify against your own service info before repair work.
- SAE J1939-73Application Layer: Diagnostics (defines the SPN/FMI fault-identifier framework)
Commonly Affected Vehicles
- Kenworth T800 with CAT C15
- Kenworth W900 with CAT C15
- Kenworth T2000 with CAT C15
- Peterbilt 379 with CAT C15
- Peterbilt 389 with CAT C15
- Peterbilt 386 with CAT C15
- Peterbilt 387 with CAT C15
- Freightliner Classic XL with CAT C15
- International 9200i with CAT C15
- International 9400i with CAT C15
- Western Star 4900 with CAT C15
- Western Star 5900 with CAT C15
- Kenworth T800 with CAT C13
- Kenworth T660 with CAT C13
- Peterbilt 386 with CAT C13
- Peterbilt 387 with CAT C13
- Freightliner Columbia with CAT C13
- International 9200i with CAT C13
- Kenworth T370 with CAT C7
- Kenworth T470 with CAT C9
- Peterbilt 335 with CAT C7
- Peterbilt 340 with CAT C9
- Freightliner M2 106 with CAT C7
- International 4300 with CAT C7
- Thomas / Bluebird school bus with CAT C7
- IC Bus shuttle with CAT C7
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