OBD-II trouble code
P2142: Exhaust Gas Recirculation Throttle Control Circuit 'A' High
An open circuit on an actuator that springs back to fully open, so nothing about the way the engine drives changes. On diesel applications the tell is at key-off: a shudder as the engine dies instead of a clean stop, because the same actuator is the air shutoff.
Quick facts
- System
- Powertrain
- Category
- Emissions / EGR
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $90 – $800
- DIY difficulty
- Intermediate DIY
Browse every code in P2100–P2199, or start from the full code library.
What does P2142 mean?
P2142 sets when the module commands the exhaust gas recirculation throttle actuator and the voltage on its control circuit stays up instead of coming down. On the ground-side driver arrangement used on most applications, that means current is not flowing when it should be, and the overwhelming majority of the time that means the circuit is broken somewhere — a corroded terminal, a broken conductor, an unplugged connector, or an open motor winding.
The practical character of this code is set by the actuator's default behaviour. The intake throttle plate it drives is spring-loaded to the fully open position, deliberately, because a plate that failed closed would choke the engine. So when the circuit opens and the motor stops receiving current, the plate springs open and stays there. The engine gets all the air it asks for. Nothing about acceleration, idle or power delivery changes in any way a driver would notice, which is exactly why this code so often sits in a vehicle's memory for months before anyone looks at it.
What has quietly stopped working is worth stating plainly. First, exhaust gas recirculation loses its authority at light load. Without the intake restriction, intake pressure is no longer pulled below exhaust pressure, so opening the recirculation valve moves little or no gas. Combustion temperatures rise, oxides of nitrogen rise with them, and on a diesel the additional soot lands in the particulate filter, which starts regenerating more often than it should. None of that produces a driveability complaint until the filter loading becomes a problem in its own right, at which point the bill is considerably larger than the one this code was offering.
Second, and this is the part that makes P2142 findable without a scan tool on a lot of diesel applications: the same actuator is the engine's air shutoff. A compression ignition engine has no throttle plate and no spark to remove, so the clean way to stop it is to take its air away. Modern diesels do that by slamming this intake butterfly shut at key-off, which starves the engine and brings it to an immediate, quiet stop. With an open control circuit the plate cannot close, so the engine has to run itself down against its own compression instead — and that produces a distinct shudder, a couple of extra rocking compression strokes, and sometimes an audible clatter as it dies. Owners describe it as the engine dying roughly or shaking the car when they turn the key off. That symptom, on a diesel, is a very specific pointer at this circuit, and it is often the only thing the owner has noticed.
The third thing to know is where the open usually is. The actuator lives at the cool, damp end of the intake tract — downstream of the charge cooler on a turbocharged engine, at the point where charge air has given up its heat and where recirculated exhaust brings sulphur compounds and condensate with it. That combination is mildly acidic, and the connector for this actuator sits in it. Terminal corrosion is the leading cause of an open here, well ahead of broken wires, and it develops slowly enough that the code often appears intermittently over a winter before becoming permanent. Opening the connector and looking at the terminals is a two-minute job that resolves a large share of these codes, and it should happen before an actuator is priced.
Common causes
- Corroded terminals in the actuator connector from condensate and exhaust residue
- Open circuit in the actuator's control wiring
- Connector unplugged or not fully latched after previous intake work
- Open motor winding inside the actuator assembly
- Broken conductor inside intact insulation where the harness flexes
- Damaged or backed-out terminal from a previous disconnection
- Chafed wire that has worn completely through rather than shorting
- Failed module output driver, which is uncommon but not unknown
- Rodent damage to harness sections routed across the intake
- Aftermarket or repair splice that has corroded internally
Symptoms
- Check engine light with no change in how the vehicle drives
- Rough, shuddering engine shutdown on diesel applications instead of a clean stop
- Engine rocking or clattering for a moment after the key is turned off
- Elevated oxides of nitrogen and a failed emissions test
- More frequent particulate filter regenerations on diesel applications
- Intake throttle position stuck at fully open in live data regardless of command
- EGR insufficient flow codes stored alongside this one
- Code that came and went through cold, damp weather before becoming permanent
- Green or white corrosion visible on the actuator connector terminals
- Normal power, normal idle and normal acceleration throughout
Diagnostic steps
- 1.Ask the owner about shutdown behaviour on a diesel application. A shudder or extra compression strokes when the key is turned off is a direct pointer at this actuator and often the only symptom present.
- 2.Open the actuator connector and inspect the terminals before anything else. This connector sits in the coolest, dampest part of the intake tract and corrosion is the leading cause of an open here.
- 3.Command the actuator with a bidirectional scan tool and watch its reported position. No movement at all is consistent with an open, and it confirms the code is current rather than historical.
- 4.Check the actuator's motor winding resistance across its terminals. An infinite reading confirms an open winding and takes the wiring out of the picture.
- 5.Test continuity of the control circuit between the module connector and the actuator connector with both ends disconnected.
- 6.Voltage drop test the circuit under load rather than relying on a continuity beep. A heavily corroded terminal can pass a continuity test and still fail to carry the actuator's current.
- 7.Flex the harness along its run while monitoring, particularly where it crosses between the engine and a fixed mounting point, to find a conductor broken inside intact insulation.
- 8.Check whether any intake work has been done recently. A connector left unlatched after charge cooler, intake or turbo work produces this code exactly.
- 9.Look for EGR insufficient flow codes stored with this one. They are usually the same fault rather than a second one, since the actuator is what makes flow possible at light load.
- 10.After the repair, command the actuator through full travel, confirm the reported position follows, and on a diesel confirm that shutdown is clean again.
Repair cost
$90 – $800
Diagnosis is $110 to $220 and is usually quick, because an open circuit is one of the few faults here that a meter settles definitively. A corroded terminal or connector repair is $90 to $280 and resolves a large share of these codes — this is the cheap outcome and it is common enough to check for first. A harness section repair runs $150 to $400 depending on access. A complete EGR throttle or intake throttle actuator assembly is $200 to $650 in parts plus 1 to 3 hours of labour, since the motor and its position feedback are sold as one unit. Where a diesel particulate filter has loaded up because the fault was left, the cost of a forced regeneration or filter service is separate and considerably larger.
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DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.