CAT Engine 2836 Fault Code: Filter Restrict Lamp short to ground
Also called Filter Restrict Lamp Short to Ground, Filter Restriction Lamp Short to Ground
Filter Restrict Lamp short to ground · ai-assisted, editor-reviewed · Last updated 2026-07-13
TL;DR
CAT code 2836 means the ECM has detected a short to ground (or excessive current) in the Air Filter Restriction Lamp circuit on C11 and C13 engines. The lamp may fail to illuminate even when a real air filter restriction exists, so the code itself is logged for follow-up rather than signaling an active restriction.
Medium severity. This code affects a warning lamp circuit, not engine performance directly. However, because a malfunctioning lamp circuit means real air filter restrictions may go unannounced, treat this as a diagnose-soon item rather than something to ignore for multiple shifts.
What does CAT Engine error code 2836 mean?
The Air Filter Restriction Lamp tells the operator when engine air intake is being choked off, either from clogged filters or another restriction. The ECM figures this out by comparing pressure readings from the Atmospheric pressure sensor and the Turbo Compressor Inlet pressure sensor. If those two readings disagree by enough, the ECM assumes restriction and turns the lamp on, while also cutting engine power as a protective measure.
Code 2836 is not about the air filter itself being dirty. It is about the electrical circuit that drives the warning lamp. One side of the lamp gets 24 volt DC from the ECM when the ECM wants the lamp lit. The other side ties to a digital return wire. If the ECM sees high current or a short to ground on this circuit, it logs 2836.
Because the lamp circuit is compromised, the lamp may not turn on even if the engine truly has a restricted air filter. That is the real risk here: you could be running with high derate-worthy restriction and never see the warning.
What triggers a CAT Engine 2836 code?
The ECM sets this code when it detects high current or a short to ground in the lamp circuit (wire 430-BU), and the ECM has been powered up for at least 2 seconds.
Common causes of 2836
- Bad or faulty lamp bulb
- Damaged, corroded, or disconnected connectors and wiring
- General problem within the engine or machine wiring harness
- Wire 430-BU shorted to ground through one of three wires in the engine or machine harness: 993-BR, 998-BR, or 229-BK
- Wire 430-BU shorted to power through one of four wires in the engine or machine harness: 150-OR, 997-OR, A700-OR, or 996-GN
- Faulty ECM
- Intermittent wiring problem
- Blown fuse
How to troubleshoot CAT Engine 2836: first checks
- Inspect the air filter restriction lamp bulb for damage or failure, replace if questionable
- Visually check all connectors in the lamp circuit for corrosion, looseness, pin damage, or moisture intrusion
- Trace wire 430-BU for chafing or pinch points where it could short to ground or to power, paying attention to routing near 993-BR, 998-BR, 229-BK, 150-OR, 997-OR, A700-OR, and 996-GN
- Check the relevant fuse for the lamp circuit and replace if blown
- Use the diagnostic scan tool's Override Parameters screen to bench test the lamp bulb independently of the harness
- If wiring and bulb check out, suspect the ECM as a last step since it is listed as a possible cause across all variants
How the code clears
No separate clearing step is listed. Once the short to ground or high current condition is repaired, the code should stop being set on the next power-up cycle after the ECM completes its 2 second check. Confirm repair using a diagnostic scan tool to verify the code no longer becomes active, and check logged history to confirm it does not recur.
Affected models and serial ranges
2836 appears in our records across 2 CAT Engine models. Match your machine by model and serial number.
| Model | Serial ranges |
|---|---|
| C11 | Serial range not listed in source records |
| C13 | Serial range not listed in source records |
Frequently asked questions
What does CAT code 2836 mean?
It means the ECM has detected a short to ground or excessive current in the circuit that powers the Air Filter Restriction Lamp on C11 and C13 engines. It is an electrical circuit fault, not a direct report of a clogged air filter.
Will my engine lose power if I get code 2836?
Not directly. The lamp circuit malfunction itself does not trigger a derate. However, if a real air filter restriction occurs while this lamp circuit is broken, the lamp may fail to warn you, so you could miss the warning that would otherwise accompany a power derate.
Can I keep operating with code 2836 active?
You can typically continue working, but you are running blind on air filter restriction warnings. Since a real restriction can still cause an engine power derate without lamp warning, get the circuit diagnosed as soon as practical.
What wires should I check first for code 2836?
Focus on wire 430-BU, the main lamp circuit wire. Check where it could short to ground through 993-BR, 998-BR, or 229-BK, or short to power through 150-OR, 997-OR, A700-OR, or 996-GN, depending on your machine harness routing.
How do I test the lamp bulb itself?
Use the Override Parameters screen on a diagnostic scan tool to command the lamp on and off independently of the ECM's automatic logic. This isolates whether the bulb and its immediate wiring work.
Does code 2836 always mean the ECM is bad?
No. A faulty ECM is listed as a possible cause across multiple diagnostic variants, but it is typically the last thing to suspect after ruling out the bulb, connectors, wiring, harness, and fuse.
How long does the ECM need to be powered before it sets this code?
The ECM needs to have been powered up for at least 2 seconds before it will register the short to ground or high current condition and log code 2836.