P0487
PowertrainExhaust Gas Recirculation (EGR) Throttle Control Circuit "A" Open
You'll usually notice a warning light along with a car that feels a touch flat and drinks a little more fuel, sometimes idling rough when it's cold. What's going on underneath is that the ECU has lost the signal to the EGR throttle control valve. There's an open circuit or a high-resistance fault somewhere in that valve's wiring, so the ECU can't command it and flags P0487. It crops up a lot on common rail diesels from around 2004 onwards.
ⓘ Information only. This page provides general educational information about fault code P0487. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0487 mean?
P0487 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Exhaust Gas Recirculation (EGR) Throttle Control Circuit "A" Open.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on, frequently the first and only thing you'll spot
- • Fuel economy creeping up by roughly 5-10%, noticeable over a tank or two
- • Lumpy idle or a brief stumble when you pull away, worse from cold
- • Longer or more frequent DPF regens on diesels
- • A general lack of urgency under load now and then, like the car's holding back
Possible causes
Causes commonly associated with P0487, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Broken, chafed, or corroded wiring in the EGR throttle valve harness. This is the usual culprit, often where the loom flexes or sits near heat
- 2. Corroded or burnt pins in the connector at the throttle actuator, very common on older diesels that have seen a lot of winters
- 3. The EGR throttle valve or actuator itself has failed with an open coil inside
- 4. Poor earth connection at the valve, which throws the same open-circuit reading as a snapped wire
- 5. A clogged or seized EGR valve interfering with normal operation
- 6. PCM driver circuit fault, rare but it does happen once you've ruled everything else out
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Scan for codes and check the live data, then clear it and drive a few miles to confirm it actually comes back rather than chasing a one-off glitch
- 2. Get your hands on the EGR throttle valve connector and inspect it properly. Look for green corrosion, melted pins, chafed insulation, and moisture. Most P0487s are sitting right here
- 3. With the ignition on, probe the signal circuit at the valve with a multimeter. You're looking for somewhere around 5V
- 4. Check the earth side. A test light or meter to a known-good ground will tell you if the valve's ground circuit is doing its job
- 5. Measure continuity and resistance through the circuit. An open or anything reading above about 1kΩ points to broken wiring or a dead actuator coil
- 6. If the wiring, connector, and earth all check out, test the valve. Replace it if it's failed. Only suspect the PCM after everything upstream is confirmed good
Common questions about P0487
What am I looking at to get this sorted, garage versus dealer? +
If it turns out to be a wiring repair or a connector clean-up, an independent garage will often have it done for somewhere in the region of £40 to £120, mostly labour. A new EGR throttle valve fitted typically lands in the £150 to £400 bracket depending on the part and how awkward it is to reach. A main dealer will charge more on both the part and the hourly rate, so the same valve job can run noticeably higher. The PCM scenario is rare and pushes into four figures, but you'd only get there after proper diagnosis rules out everything cheaper. Get a couple of quotes before committing.
How do I work out whether it's the wiring or the valve on my motor? +
Start at the connector, because that's where most of these live. Unplug it and have a good look for corroded or burnt pins and any moisture sitting in there. Clean it up, reconnect, clear the code and see if it stays gone. If it does, you've found it. If the code returns, get the multimeter on it: check for roughly 5V on the signal wire with the ignition on, confirm a solid earth, then measure resistance through the circuit. A clean signal and good earth but an open reading at the valve points to the actuator itself. No signal getting to the valve means the fault is back in the loom or the PCM.
Can I fix or clean this myself? +
The cheap end is very doable at home. Cleaning a corroded connector or repairing a chafed wire is the kind of job a confident DIYer can manage with basic tools and a multimeter. Bear in mind P0487 is an electrical circuit fault, so a tin of EGR cleaner won't clear it on its own, even though a gummed-up valve can make matters worse. If the testing shows the valve or actuator has failed internally, swapping it is usually a bolt-on job, though access on some diesels is tight and you'll want the codes cleared afterwards.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →